I second this. Spend time around horses (even take lessons at different places for a while) before you jump into ownership. Even though you intend to board your horse, it doesn’t sound like you know enough to be able to catch if the boarding barn is doing something wrong.
You can volunteer at a rescue, take lessons, work with facilities that provide horse assisted therapy, get a part time job at a barn.
Once you’ve put in some hours around horses, you’ll likely find someone who can help you evaluate a horse for purchase and you’ll have a much better idea of the expenses involved.
Unless you want to spend a lot of money on a trainer, remember that a cheap horse isn’t always cheap. A child safe, steady, been-there-done-that mount is worth the money asked for them. On the other hand, just because someone asks a lot for a horse, it doesn’t mean they’re worth that. Some people slap a ‘name’ (cough rescue cough) on a horse then demand an insane price (or adoption fee) for a horse that really isn’t worth the money asked.
This is why you need to work with an experienced person that you can trust who can help you evaluate the horse. Be aware, there are some long acting drugs that can ‘sedate’ a horse for a period of weeks, so always buy from someone with a good reputation.
OH, an IF you consider adoption, READ THE CONTRACT! READ THE CONTRACT! READ THE CONTRACT! READ THE CONTRACT! READ THE CONTRACT!
There are some real looney contracts out there and once you sign it, the courts will enforce it. Don’t ever sign something thinking “they’d never do that to me”. I’ve seen some total loons that are sweet as pie until you’ve adopted THEIR animal… suddenly they’re on your property, in your face constantly and trashing you all over the internet.
Your first priority should be a SAFE horse, don’t let looks or a sad backstory sway you into taking on a rank or dangerous or untrained horse unless you have the extra money to pay trainers and vets to bring the horse around right and the willingness to spend the time on such a project.
(If you’d posted that you had 10+ years breaking out colts and were totally comfortable with horses, my attitude about much of the above would be different. But, I see too many novice people taken advantage of by people in the horse industry.)