To my way of thinking, the only reason to buy a stallion is to stand him at stud. If you plan to do that then you need to spend a great deal of time researching bloodlines, what crosses with what, and how to successfully and safely run a breeding operation. Then you need to start searching for the very best horse you can get you hands on for the wad of cash in your pocket. Then you will need to spend a great deal of money promoting this animal to attract mare owners. And then pray that mare owners will beat a path to your door.
A responsible breeder wants to put the very best foals possible on the ground. With all the unwanted horses out there now what is not needed is more added to the supply. Breeding is very serious business. It sounds like you have a lot of homework to do.
But if you want this horse for a pleasure mount, buy him, geld him and enjoy him.
If you ever find yourself in a fair fight, it's because your tactics suck. ~ Marine 1SGT J. Reifinger