I worked out roughly how much I'D spend a year on a horse.
Which is aroud £2000 for rent, shoeing, worming, insurance, dentists and bootster injections. Not including feed or vets bills, because both vary so much. Also not including tack/kit.
But yes, that'd be the very cheapest/basics of horse-owning.

I get rent and hay really cheap where I live, and sometimes cheap shoeing, which is a good bonus.