I just did the same thing at Walmart yesterday afternoon. Went back to the electronics department to see what they had and there was a bunch of Nexus 7 locked up in cabinet.
I couldn't believe they had them in stock and bought one right away.
The clerk said they just had gotten them in that morning. I asked if they had a demo unit to try out because I usually do not like to buy tablets, etc. without trying them out first, but he said they get demo units separately, if they get them at all. So I bought one to try it. Couldn't resist the urge to try the nexus 7 and jelly bean. Figured if I didn't like it or got a faultly unit I could always return it. So far I love it!