Legally I have no idea if they have to sell it for that price. It's usually based on company policy, I think.
For example, my cousin once bought a whole bunch of office chairs at a PACE Club (like Sam's) for like $2 each when they were supposed to be marked $20. And I got a few whole chickens at a grocery store once because they were marked $.39 each instead of $3.90.
But several months ago when I went to buy a couple of computer cases at CompUSA, they had the cases I wanted marked $99.95 and when I got to the register it charged me $149.95. I could have paid the extra, but I was pretty upset because they had a massive display of the cases out front plainly marked $99.95 and I was pretty happy with the price. Well, anyway, instead of giving me the cases at $99.95 each they insisted they wanted me to pay the $149.95 so I just walked out. They not only lost a $300 sale that day, but they lost out on the two laptops I purchased a couple of months later, when I went to Best Buy instead.
