There are many different ways to acquire a Thoroughbred racehorse.  However before making any type of purchase you should seek guidance from someone with expertise of purchasing horses such as a trainer or bloodstock agent.

Seek Guidance 

The best way to buy a racehorse is to choose a trainer and allow them to find the best horse to fit your aspirations of ownership.  A trainer can help you sort through information on horses being offered for sale at public auctions or through claiming races at all racetracks.  Your trainer will also arrange for pre-purchase vetting and after purchase insurance options.

Purchase from or Partner with your Trainer

Trainers go to horse sales and buy horses for owners and they may also purchase horses that catch their eye on spec with the expectation that an owner can be found.  The trainer may offer to sell you or partner with you on such an acquisition.

Horses bought through auction

Every year horses of all ages are offered at various auctions throughout the industry.  Thoroughbreds are not eligible to race until the age of 2 therefore if you buy a younger horse at auction you must have access to board them until they are old enough to start training.

The most popular age to buy a horse at auction is when they are yearlings (horses that are 1 year old). At this stage you would need to ask your trainer what it would cost not only to purchase the yearling but also to board the horse until training.  

There are also two-year-old in training sales.  These are horses that are eligible to race and are already in training (for purpose of selling) but have not yet raced.

There are also horses of racing age sales where you can purchase a horse at auction which has already been racing.  These can usually be found at a mixed sale which also includes weanling horses (horses that less than a year old) and broodmares (female horses sold for breeding purposes).

Claiming

Claiming races are run throughout North America and your trainer can put in a claim slip on any horses that run in claiming races.  There are different levels of claiming races where the cost to claim the horses vary.  If more than one trainer puts in a claim slip for the same horse a draw will be made to determine who gets to claim the horse.

Private Purchase

Some horses can be purchased privately between an existing owner and a new owner.  A bill of sale should be included along with the transfer of the Certificate of Registration.