Costs are arguably the most important consideration for investors in choosing investment funds.
"In the short term, the impact of costs may appear modest, but over the long run, investment costs become immensely damaging to an investor's standard of living," wrote John "Jack" Bogle, founder of Vanguard Group and a pioneer of low-cost passively managed index funds, in a Financial Analysts Journal article last year (to view the article, click here).
Read MoreHow much is that mutual fund costing?
The compounding of costs from annual fund management fees, as well as distribution and trading costs passed on to investors, has a very big effect on the total returns that investors experience.
"The good part of the huge universe of fund options is that investors can use screens and be very picky with their selections," said Kinnel at Morningstar, who noted that fund costs are the first criteria he considers in developing Morningstar fund ratings.
Information on fund costs is readily available from sources such as Morningstar, as well as the websites of most large investment companies.