Hey, now i'm going to talk from the buyers point of view! I have bought all my horses on payment plans, and was allowed to bring them home with as little as $500 down (say on a $2500 horse). (ok so I did pay for ONE in full but on a credit card so I am still paying that one off LOL!). Anyhow...I just wanted to say for me, purchasing a horse on a payment plan and being trusted to take home the horse while paying is just awesome! Not only do I get to enjoy bonding with my new little him or her, but, I get to show the seller that I am trustworthy for my word of paying off what I owe. I have never not paid in full. Sure, things happen and once in a while a payment may be a few days or a week late but, I always kept in touch with the seller to keep them aware of what was going on and that the payment would be mailed on X date for sure...none of that "oh it'll be in the mail" and it is never received kind of crap. I do feel really bad when a seller is taken advantage of and someone decides oh, they have the horse and now they don't need to send payment anymore! That makes honest buyers such as myself, be in more strict situations and guidelines.
One thing for sure, if you sell the horse on payments and let them leave before being paid in full, do NOT send along registration paperwork. Mail the registration papers only after the horse has been paid in full, otherwise that's when you can get the people who think they have everything, horse and papers, so why send anymore money?
Good luck! Just know that there are more of us honest, trust-worthy buyers out there, than there are people who would rather cheat you. Just be cautious, make up a good contract that covers YOUR butt in all areas, and know that your horse is going to a good home!