NEW YORK ( TheStreet) -- The most exciting IPO this year has been that of retailer Five Below ( FIVE), which went public about five weeks ago. Shares rose 53% on the first day of trading and are up nearly 90% over the $17 offering price, ranking Five Below as the second best performing IPO in the past three months. It was also somewhat of a breath of fresh air for an IPO market that has been stung by the Facebook ( FB) debacle. Five Below stores have become a phenomenon in our house and a frequent stop for our teenage children. I have not seen such a buzz about another retailer with the possible exception of Costco ( COST) (but that's mainly due to the abundance of free samples that are handed out at Costco stores). Truth be told, I like going into Five Below stores as well and often wonder what it would have been like if the chain had been around when I was a teenager. I'm sure I would have spent a lot more of my hard earned lawn-mowing and paper route money. Interestingly, Five Below was founded the same team behind Zany Brainy, once a publicly traded chain of educational toy stores that filed for bankruptcy in 2001. It happens. Zany Brainy was a great concept and another chain that we frequented. But the retail business is difficult at best, and the competition is intense. Now, I don't believe that Five Below is destined to go the way of Zany Brainy or that it is a fad like Green Mountain Coffee ( GMCR), SodaStream ( SODA) and Facebook. I believe the company is here to stay and has solid growth prospects ahead. But I am not a fan of Five Below's shares at these levels. That may sound strange given my positive sentiment about the stores and belief in the brand, but it looks to me as though a great deal of growth is already priced in at this point, leaving little room for error. I just can't justify paying more than 5 times trailing revenue and 50 times 2014 consensus earnings estimates (The company's fiscal year ends in January) for these shares. Sometimes there is a disconnect between price and valuation, and I believe that's the case with Five Below.