I would just rather buy two poor conditioned horses that have uncertain fate's than go & buy a young colt from a nice breeder or something.
A good breeder spends a lifetime breeding good horses that will excel at what they are bred for. When people opt for cheap horses with unknown breeding, health and soundness, your chances of getting a horse as good as you can buy from a good breeder are somewhere between slim and none.
You can buy good untrained young horses at a sale, frequently registered or with a registration application and get a decent prospect if you know what you are looking for. Too many buyers frequently buy a horse because they feel sorry for it. Like a 'free' horse, it is usually the most expensive horse they could possibly acquire.
If you do buy a horse at an auction, don't hesitate to take it back to the next auction when it proves to be NOT the horse you thought you bought. You do not need to keep a money pit or any horse that does not work out to be suitable for what you need. You can put a lot of good money after bad if you are not willing to take one back.
I buy most of my older trail string horses from an auction only 3 miles from my house. About 2/3 of them go back 2 weeks later. They are unsound, wake up from the ACE, (that's what we named one of them) or have health or other issues that I do not need. I actually have 4 or 5 horses right now that were 'rescues' from the killer buyers (including the one in my profile with my 4 year old granddaughter riding), but most have gone back. I'm close and don't lose more than $50.00 -- a few make a $ or two. I'm not a trader; I want to only buy horses that will work for the job I have for them, will not have health or soundness issues and will last. Some of the geldings in my trail string have been here more than 10 years -- one for 13 years. Most came from the auction, but then I am not looking for 'performance prospects'. And by all means -- quarantine a new horse for 2 weeks and only handle it AFTER you have fed, handled and worked every other horse you are going to touch for that day.