In Ca, we have Casual Dining which carry stool at a variety of heights. You can also check out www.homedecoraters.com on line. If you cannot find one in the exact height you require, try looking for a wooded legged stool that is higher, but that you can cut to meet your needs.

I would also check out thrift, consignment and charity stores to see if there is something you can redesign for your purposes.