I second the rec to check out the Del Mar website. That is a wealth of information on the thoroughbred racing industry. The vast majority of the horses that make it to the higer grade stakes races, and on upwards of the "triple crown" caliber as you put it are generally (but not always) bred, foaled, raised in KY on any of your premier breeding farms such as Claiborne Farms, Three Chimneys, Golden Eagle Farms, etc. However, TB racing has caught on and become quite popular overseas as well, especially in the arabic nations and in Japan. Keeneland has a fall and a spring yearling sale which is where the vast majority of the horses to be tried on the track will change hands. Horses at this sale go from tens of thousands of dollars on up into the millions, although the most successful horses tend to be ones that don't exactly stand out as good or bad prospects. Many of the people involved in the racing industry from an "owners" standpoint are part of a conglomerate or corporation of owners pooling their money together to buy the horse(s), hire the trainer, later on pick/hire a jockey, pay for nomination fees, etc etc. For a horse to make it to Triple Crown Level, he needs to be with a knowledgeable and experienced trainer who will enter him in the stakes races needed to build his reputation, match him against competitive horses to prove his ability and later on prepare him for those tougher, longer, more competitive matchups.