Getting married isn't cheap, but it can break the bank in more ways than one—especially if brides and grooms fall prey to scams.
Experts say engaged couples and newlyweds are often targets for thieves and con artists. In part, it's because they're spending big bucks. Last year, the average couple spent $25,656, according to The Wedding Report a market research firm. And many couples are receiving nearly as much in gifts from friends and family.
More than that, most couples are in unfamiliar waters—they've never hired a DJ or bought a wedding dress, said Alan Fields, co-author of "Bridal Bargains." They don't have a go-to provider or maybe even people to ask for referrals, which makes it easy for less scrupulous individuals to take advantage.
"There's always a new group of customers, and some people don't do their research," he said.
(Read more: Recouping wedding costs lost to the shutdown)
What to watch out for? Experts say these five problems could cause big problems for a couple's Big Day.
1) Faux vendors
Couples, you can say what you will about a caterer's dry cake or a DJ's bad song choices. But gripes about a legit vendor who failed to meet expectations pale in comparison to (happily, rarer) complaints about vendors who take your cash but don't do anything at all. Period.
Earlier this year, police in Little Falls, NJ, charged photographer Michael De Rubeis with theft by deception and impersonation, alleging that he—while operating under the name Michael J. Distasio—accepted $140,000 from clients and did not deliver their photos. The New York Attorney General's office made similar allegations when it sued De Rubeis in 2003 for photography and video work contracted under a number of business names. (De Rubeis could not be reached for comment.)
In all, nearly a quarter of wedding insurance claims last year pertained to problems with a vendor, according to Travelers. That tally comprises a range of issues, but one of the biggest is non-delivery and no-shows, including vendors who go out of business, said Ed Charlebois, vice president of personal insurance for Travelers. "I would hesitate to call them scams, but that, to me is troubling," he said.
"It's obviously something pretty important to be checking references," said Anja Winikka, site director for TheKnot.com. Couples should check ratings on review sites such as The Knot's WeddingChannel.com and WeddingWire.com, and ask the vendor for recently married couples to speak with.
(Read more: $ave Me: Spotting fake online consumer reviews)
Then pick the right payment method. "We really do suggest, pay with a credit card when possible," Winikka said. The Fair Credit Billing Act gives cardholders the right to dispute charges, and usually, get their money back, if a retailer or vendor fails to deliver on a paid-for item or service.
2) Gift theft
Engaged couples don't just spend a lot—they're on the receiving end of some valuable gifts. Attendees give an average $144 to a family member who's getting married; and $97 if the bride or groom is a friend, according to American Express. If the guest is affluent, the average gift value jumps to $251.
Multiply that by the average guest count of 136, factoring in that one-third of those gifts are given in cash at the reception, and you have an attractive target for thieves. Last year, one Pennsylvania couple had $10,000 worth of cash and checks stolen; this summer, wedding crashers in Minnesota allegedly made off with a box containing more than $7,000 in cash, checks and gift cards.
In fact, travelers reports that 10 percent of wedding insurance claims in 2012 involved theft. "That's [usually] theft of wedding gifts at the venue, when people bought them there," said Charlebois. Other targets: The wedding bands, and gifts intended for the bridal party.
While wedding insurance policies usually cover theft, experts suggest couples take other precautions, including placing the gift table away from exits and asking a friend or family member to take charge of collecting and securing gifts.
3) Home burglary
Theft isn't limited to items at the wedding. Burglars may target the homes of couples celebrating their nuptials, or away on their honeymoon.
Wedding announcements in newspapers and details on wedding web sites can provide would-be thieves with a solid timeline of when couples won't be home, as well as personal details that can help identify a home address, Fields said. Burglars who break in during the honeymoon may help themselves to unopened wedding gifts as well as valuables typically kept at home.
"People have been doing this for years and years and years," said Christopher Falkenberg, the founder and president of Insite Security. Falkenberg, a former Secret Service agent, said it's the same opportunity that leads burglars to peruse funeral announcements and watch for piled up newspapers that signify you're on vacation. Social media mentions and virtual check-ins widen the scope.
That's not so say couples shouldn't announce their wedding or take their honeymoon in secret, Falkenberg said. "You can't turn your life on your head for security issues," he said. But couples should take steps to limit vulnerability, including locking up valuables and, for the honeymoon, halting mail and newspaper delivery and having a friend or family member stop by regularly. He said using devices that mimic the flicker of a television or a dog barking can also deter burglars.
(Read more: What wedding crashers are costing the hotel biz)
4) Counterfeit dresses
In 2012, the average bride shelled out $1,444 for her dress, veil and accessories, according to The Wedding Report. So it's not surprising that brides look for ways to cut that cost, shopping around for lower prices on that dream dress from an online-only boutique or from listings on a marketplace or message board.
Snagging a $1,200 dress for $200 isn't always a steal, however. According to the American Bridal and Prom Industry Association, as many as 600,000 counterfeit wedding dresses were purchased by brides in North America last year.
Counterfeits might illustrate listings with the same photos as designers do, but brides are buying something very different. "When the dresses arrive, they're made of inferior materials," Winnika said. They're typically less elaborate than the real deal, and may be poorly constructed. Worse, sometimes the dress never even arrives.
And if the bride isn't happy? "The customer service is nonexistent," Winnika said. Usually, the dress is nonreturnable, or can only be sent back at the buyer's expense for shipping and with a steep restocking fee.
To avoid fakes, look for authorized retailers on the dress designer's site, and check consumer reviews. Brides should also check the retailer's return policy, and make sure there's a working phone number and email address in case of order problems.
5) Fake couples
It's not just brides and grooms who risk getting scammed. Vendors have encountered their share of problems, too, from criminals posing as engaged couples.
Stephanie Martin, owner of One Fine Day Events, says it's not unusual for her to hear from couples planning a destination wedding--her firm coordinates events in San Francisco and Lake Tahoe. But when she exchanged emails a few years ago with a British groom offering to send her $45,000 up front to make all the wedding decisions on behalf of him and his bride, it rang alarm bells.
"They said they didn't have time to do [the planning]," she said. "My clients generally want to be involved, and make decisions."
A web search for the would-be client's name turned up pages about email scams. "They promise to wire money, but they really want your bank account information," Martin said. In a variation, the "clients" send a too-large check and ask the vendor to wire back the excess, only to disappear with that cash before their check bounces. Vendors' best recourse is to leave such fishy missives unanswered.
—By CNBC's Kelli B. Grant. Follow her on Twitter @kelligrant