I'd wait for somewhere else to have it on sale.
Walmart has a habit of cancelling orders and not telling you until you are in the store trying to pick your orders up.
That's the problem. Most places are sold out new and haven't received new shipments in quite some time. Among major outlets, only Best Buy ($39.99 online only) and Walmart ($19.96) have it. Walmart being the cheapest I've seen the game new. Amazon market sellers are already starting to jack up the price too.
I think this will be as cheap as it gets. Best Buy may hold a sale on it...that is, if it doesn't sell out before they put it on sale.
Also, try Fed Ex Office pick up if you have one near you. I have one around the corner, much closer than my nearest Walmart. Orders are shipped there for pickup and are shipped from their warehouse. Never had an ordered canceled using this pickup method.
EDIT: Just bought...not taking the chance.