The link below has an awesome guide on what you need to make tack, the locations of the crafting buildings, and how much it would cost.
You can make two types of tack: English and Western. You can craft English tack (bridles, saddles, and saddle pads) in Witherton. And Jungle Isle's craft shop has the Western crafting section. It will have directions on what you need for each item.
Wington Tack Shop
You can buy Heavyweight tack in the Carrotton Gear Shop for $1,020,000. ( Need more help? Check out http://tipisle.ucoz.com )
Jackrabbit tack costs about $1,100,000
There is unlimited draft tack in Wington, Bird Isle.
Jack Rabbit tack is found in the tack shop on GlacierTon.
You can craft English Saddles and tack in Witherton, Rider Isle. And you can craft all western tack in Tropicton, Jungle Isle.
Saddle. (Horseisle!)
Treeton or Appleton
Fireball tack costs approximately 1.2 million.ChilliFlame -Pinto-
In the town Witherton on Rider Isle.
There is an unlimited supply of both Fancy and Glorious tack in Shellton, on Turtle Isle.