Short answer...No, they don't have to give it to you for that price.
Long answer (with experience)...
A few years back we were moving some stock around. One of these was a standard glass case with tape recorders in them. Well, to save time, we didn't take out the stock and instead moved it, which caused some of the recorders to shuffle around. That whole week, if something "looked" out of place by a hair, we generally apologized about the price because we were moving, the customer always agreed and we never had to mark down a price. Well, in that glass case, one of the tape recorders, which was going for around $60 slid over and fell onto a $25 or so recorder. It was about halfway on there to be exact.
Anyways, a woman comes in and wants to see the "$25" recorder so I grab the real one. She says no, the other one. We talk about it and she finally says "So am I going to get it for $25?" I say No because it's marked for $60. She throws a fit and I got probably the second best yelling I had ever gotten in retail. So she asks me the same question again. I say No and she wants to speak with a manager. They were busy so I grabbed a supervisor. She said No too. The woman starts saying that it's against the law and we HAVE to sell it to her. She storms out and says she'll never shop there again. Oh well...
So I look into it and it really isn't against the law. Since it's the store's stock, and we can say who we want to sell it to (to the public, but there can be exceptions). Fact is, the store doesn't have to sell it you if they don't want to. The only thing that is really against the law in retail is bait and switch and having a lower number of stock than what is advertised (so if you see a $299 TV on sale for $79 at Circuit City and wait until Wednesday to get it, don't complain, most likely they ran out of stock on Sunday) Same thing if they listed "25 ONLY IN STOCK"
Wal-Mart would probably argue that the price could've been placed there by anyone and typically stores won't match the price because anyone, even you, though you're not suspected, could switch it.