Thoroughbreds are actually not a great choice for barrels. They can and do work well in certain situations, but the best of the best are Quarter Horses, Paints, and a few Appaloosas. Some Arabians and Arabian X's do well, also. If you want a prospect you're going to be looking in a fairly high price range, most go for around $3k at least in my area. I wouldn't use an auction horse, unless it's a youngster. My mare is just a grade paint, but she does well. My gelding is a papered Appaloosa, and he has the speed and agility to do it. I also never, never work the pattern at home. I work around one barrel. And cones. Don't necessarily look for speed, but turning ability and agility. It is far better to run a slower clean run than to run a fast run and knock a barrel.