This is a great question. I am always in the market for one that doesn't cost a fortune and go up w/ minimal effort.
I had the one from Walmart, 10x10', but it did not have the sides. The construction was flimsy, but had a lot of space underneath. It kept the sun off my neck and protected my gear from the freak Florida *surprise* thunderstorms. I could also manage to put it up and take it down w/ little help.
I say "had" because it could not withstand my drunk friend crashing into it while playing tackle cornhole.