there is a horse rental place just outside of cody and i cant think of the name of the place right now.{sorry that i cant remember}
a lot of the outfitters in the area will lease there horses out such as ishawooa outfitters. i have seen people put ads in the paper, or what we have called the penny pincher where you can put a add in and put looking for horses to rent. might find someone that lease them cheap to ya.