We do, however, have a baby pool that we picked up at Babies R Us when we went to buy her a nice, new, more comfy carseat. It was only $7.
I didn't have any sand, but I did have a huge bag of white rice that was still halfway full. I'd bought it and used some to make rice warmers a few years ago for Christmas presents, and the unused rice has sat in my craft closet since.
A perfect fix for a sandbox-less household. And when the weather decides to warm back up, I'll throw the rice back in the bag, and fill the pool up with water... and won't that be fun too!