Want a horse but...? HELP PLEASE?

I have a mini horse now and I board him at a family friend's so I don't really have to pay a set board. I want to get a horse as a companion, like a larger horse, such as an injured thoroughbred that I don't have to ride, and I want to visit it, but I don't live in a super-rural area and I don't have the money to board and pay vet bills constantly. What should I do? I saw a program online for $600 where you can ADOPT a horse but you don't get to own it... Help!