You would be a lot safer to slow down a bit and first find a new stable/trainer that you can trust. Once you are sure of your new trainer, ask for help in finding you the right horse for you. It is traditional to pay a trainer 10% of the purchase price for whatever horse you end up buying but trainers will usually be willing to travel with you to see several.
The barn owner you have now is obviously not to be trusted-this is a $500 horse in my area and for $8500 you should be able to find the horse of your dreams!
Be careful not to travel too far from home in looking. Ideally you want to ride a horse several times on different days before you shell out any cash.
We have had several Western Pleasure horses sold out of our barn by an abusive trainer that were completely broken down mentally and physically. They were all tranquilized and had their lame knees & hocks injected before potentially buyers showed up. I heard her say to one of the owners of a horse she sold "make sure you cash that check today". This trainer has left the barn but there is one more horse left for sale on one of the big sales websites for $10,500-he is permanently lame and bucks his owner off twice a week. In other words, just because a horse has a high price tag on it doesn't mean it's safe to buy it!!
This is injecting of horses unfortunately common practice in my area for all riding styles.