I've owned a horse when I was young thanks to my parents. Aside from there high maintenance there amazing animals and Apache was my best friend.
But that was over 20 years ago. Cost now are different than back then. I couldn't help you with prices.
They need room to run and exercise and play. A nice shady place to rest in the day when its hot. Barley & oats, Salt cubes and feeding hay, grass. For treats, Carrots, apples. Lots of fresh water and one bottle of Beer for his birthday. Well my horse liked beer... so don't look at me that way...
If you want to learn then go to a farm that has horses. Learn what you can from them by asking questions and watching. Even better volunteer help maybe you learn some tricks. Understand the responsibility first before taking on an animal that size. Its not a dog. In the end the reward is worth it. Owning a horse was one of my happier time in my youth.
Goodluck dude,
WH