What to look for when buying foot bath?

After trying an ionic foot bath at a health expo, I've decided to purchase one, but don't know what to look for or what's important. Can you give me some ideas on brands and features to look for? Also, someone on this forum mentioned using kitty litter tubs and bags - is this cheaper than buying the bags and tubs offered online?

It was really interesting to see differences in the water of 10 people whose treatments were started at the same time. One guy had small worms/ parasites in his water and was pretty grossed out - he was asked if he worked outdoors and it turned out he's an arborist. Tweet