Update: We went ahead and bought one of these. They had them at Walmart for $50. I'll keep an eye out to see if they come down any more though.

It was going to be a surprise for the kids, but my wife left it in the back of the Sequoia and of course they saw it when she was getting out groceries. At any rate, I'll post a review once the pool is completed and we've had a chance to use it.