Only half-joking here: inflatable kiddie pool, bag of softener salt, and a tarp? Total < $100, brine should keep much from growing so I wouldn't think it would need too much maintenance.

There's also the issue of keeping it at body temp.

Usually you do. I was able to try one of them once via a Groupon or some such local coupon.

It's about $30 per hour in my area. I'd go every day if it were cheaper :)