How to buy a racehorse? Watch and learn. 

I made this video and to answer some of your questions. Some consigners represent smaller breeders, some breed the horses themselves. She likely breeds a few herself and consigns for other breeders. Her service is getting the horse from a breeder and marketing it for a sale through a sale like OBS. Some horses go for 5k and some go for 500k. More expensive horses come from a better bloodline, meaning their sire (stud horse) has performed well. A good dad with a good mom makes for a (potentially) good horse. Most bloodstock agents have an eye for a good horse and follow the brothers and sisters of their horse's active record, showing that younger horses' potential. Lots to learn!