I live in Central California, and here are the monthly expenses for my 6-year-old boy, Mudpie. Feed
Bales of alfalfa - $72 (1 bale [$18] typically lasts 1 week)
Bags of cheap brand senior feed - $30 (1 bag [$15] typically lasts 2 weeks)
Supplements - $85 + (I buy a month's supply at a time through SmartPak)
[he gets U-7 Gastric Aid, SmartHoof, & CortaFlx] Board
Co-op boarding $100 a month (do-it-yourself)
(morning feeding & cleaning) $150 a month [$5 a day] - I have school so I can't get to the barn in the mornings Farrier
New shoes $100 (once a month, due to Mudpie's weak hooves)
I can't say what yearly vet bills are, as they are highly unpredictable with my accident prone boy, who seems to get seriously injured one way or another on a regular basis.
But the yearly expense for the basic care of my Mudpie is: $6,994
Granted, right now it's a bit inflated, but my step dad will pay for all that as long as I do well in school. So I'm all over that! ;) I'm just filling him up with good care and love while I have the opportunity!
That's a wee bit more expensive than your "average" horse care, because Mudpie tends to be rather high maintenance, but it's not all that far off!
Just little expense report, so you can get a wider range of idea on what a horse can cost.
That's not counting all the tack and equipment, entry fees, etc. :)