These guys still make hoof boots
http://www.ponyplayranch.com
The boots in the Tori Amos video were made by a British designer, Fleur Oakes, who doesn't advertise them. This is probably her website:
http://www.fleuroakes.com/
As you can see, she's since moved on to textile art. Maybe if you ask nicely, she'll make a pair for you. Maybe not.