but yes, I agree, and I've made a program/schedule and with the amount of feed I give my Frisian warmblood and some extra cost of fuel time tack etc. etc. I will have to sell the horse for only $4000 with a $1000 profit I also have a training program as a guide, all depends on the horse though!
This is my opinion, if it helps. I'm Australian, and this is what I think. I wouldn't buy a OTTB for $4000. I know few people who would, and the ones that would go for that much would have to be exceptional (for hacking) or very experienced (like an ideal pony clubber). People interested in competing probably won't go for a TB, or if they are serious, will train it up themselves, or buy from a known trainer. Pleasure riders may get a TB, but they wouldn't want to spend that much, nor would the average pony clubber. To sell a horse with only two months training you would need to (ethically) sell it to an experienced rider, but I don't think an experienced rider would spend that much on an OTTB.
Who is your target market?
It's a decent idea in theory, but I really think it practice it doesn't work out so well. Even if you work out all the costs, it might take a month or two just to sell the horse, which seriously eats into your profits. If the horse gets injured, again vet costs could completely take up your profit. If you make $1000 profit, you could work that out at 65 hours worth of work at about $15 an hour (low wage). But having a TB for approx 70 days you'll likely put what, two hours for riding and care per day? That is about $7 an hour for the work you do if you sell the horse quickly, and if there aren't any extra costs.
For that price, you can pick up a real nice, well rounded and well trained horse if you look around. And I have known people who buy their own OTTB for $300 off the track, and train that themselves. I just can't see a lot of people paying $4000 for what you are offering.
Yes, you see adds in Horse Deals etc. for horses like this - but just because they are advertised at that price, and for sale, doesn't mean that they are sold for that much, or that they are sold at all. By all means try it - you may be successful, but don't count your money just yet, and be prepared to fund the horse for a longer period if needed, or take a loss.