In full disclosure ....I'm anti Wal-Mart for anything ....they kill local small town economies / and don't treat their employees very well ( in my opinion ) ....so I wouldn't buy anything from them ...ever .../ regardless of price ...
However, sometimes the big box retailers - Cabelas, Sportsmans Warehouse, Dicks, etc ... (do offer some guns that are a little different than standard models ...so you do have to be careful ...look at the specs...
In my opinion ...one of the best pump guns on the market is the Browning BPS Hunter model with a 28" barrel. A couple of things I really like about it ...its a very smooth action, very strongly built ...but it has the safety on the top of the tang ...making it very easy to reach even with gloves on vs 870's on trigger guards / they make the stock "cast neutral" so it doesn't favor a rightie or a leftie ...and it ejects out of the bottom ( so a leftie or a rightie can shoot it ) and all the hulls are at your feet.
http://www.browning.com/products/cat...unter-firearms
They're retailing new in box around here for under $ 600. At least check one out before you decide.