The highest valuation I've seen for a NM+ copy of Marvel's 'What If...' #1 is from Overstreet, the regularly published comics book value guide, which values this at $68.00.
As is always the case with comic book collecting however, the value of a comic isn't necessarily the price you would be able to sell it at.
Selling comic books as an individual for fun is a lot different to selling as a professional comic book dealer, who are aware of every tiny detail concerning the quality of the comic, and need to make a living from selling such items.
Some Seller's Prices for What If #1
Newkadia.com lists What If #1 in Very Fine condition at $19.00, while Comicbookrealm.com gives a price of $30.00 for a Near Mint copy, and Nostomania.com values What #1 at $21.10. If you are confused as to comic book gradings and how you copy might shape up, nostomania provide a guide to grades here.
Just to show you how difficult it can be to sell a comic at 'valuation price', a copy of Marvel's What If #1 is currently on sale for £7.00 on the UK site for eBay ($12.65) but has yet to attract a bid.
Why not keep the comic and build your collection? Here's a few tips from one of YouTube's geekiest geeks to help you out: