It isn't often that a CEO comes out and says "our stock price is kind of high right now." But that's exactly what Tesla CEO Elon Musk told CNBC's Phil LeBeau on Thursday at the company's "gigafactory" announcement in Nevada.

It wasn't the first time Musk has spoken about his company's valuation. Last August Musk told CNBC that Tesla's valuation was "more than we have any right to deserve."

While it may be unusual for a CEO to comment about a high stock price, traders consistently use valuation as a tool to determine whether or not to invest in a stock. So which companies do the pros think are just too pricey to purchase?

On Friday, CNBC's "Fast Money" traders each picked a company they think is overvalued at current levels.

Tim Seymour of Triogem Asset Management said that while Netflix's recent metrics have been great, the company is overvalued because "all the best is priced in." According to Seymour, "They're a victim of their own success because the comps start to get very difficult."

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OptionMonster.com's Pete Najarian picked Caesars as a stock that's too expensive to buy, despite the fact that it's trading near 52-week lows.

"This is a company that's got $24 billion right now in debt, so I really am concerned," he said. Najarian said that although he likes the company's Las Vegas properties, the stock still has "plenty of room to the downside."

Brian Kelly of Brian Kelly Capital chose Amazon as a company that's overvalued, but said that the market has largely ignored valuation as reason not to buy the stock.

"This kind of points out that sometimes valuation doesn't matter … the market has perceived that growth has trumped value in this case," he said.

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Kelly said that if the market starts to lose faith in Amazon's growth story, then it may be time to sell.

Finally, Guy Adami of Private Advisor Group chose used car website TrueCar as a name that's overvalued at current levels.

"The stock has been on an absolute tear," he said, "I think this has gotten ahead of its skis."

—By CNBC's Michael Newberg