I’ll further this discussion to say that if your trainer thinks it is a good idea for you to buy this horse, she probably does not have your best interests at heart. In my opinion, very few professional trainers do. They are in business to make money and that is the primary driver for most of them. Your trainer sees an opportunity to make a quick sale on this horse.
Having said that, not every trainer is like this. Ask around and find the barn with long time clients. And by long time, I mean 10 or 20 years with the same trainer. I’ve also noticed that trainers that own their own farms seem to be the most ethical (they can’t pick up and move barns easily, unlike freelance trainers). Another thing to look at is their fee structure. Most trainers charge a commission to find you a horse, which means the higher the purchase price, the higher their commission. Obviously there’s an incentive to tell you that you have to spend more. My trainer charges a flat hourly rate when she looks for a horse for a client, so her fee is the same whether the horse is free or $50,000. (And she helps clients at both ends of the financial spectrum).
Keep riding with your trainer, by all means. Just be very very wary when she suggests a horse for sale. You could do things like volunteer with your local Pony Club so that you can get hooked in to that network of horsepeople. Once you do that, ask around for trainer recommendations (as well, you can probably see some of them in action).
Finally – come back to COTH! There is a world of good advice here, and even though we have a reputation for being a tough crowd, people that are new to the sport and want to learn are welcomed with open arms.