So I have 3 horses, but I mainly show/ride only one of them. He, of course is the most expensive one :P

Board (self care): $110 per month at school=$990(9 months)
$150 per month at home=$450 (3 months)
Board Total: $1,440 per year

Feed: Strategy per 50lb. bag is $13 (4 lbs a day (2lbs twice a day))= $33 per month
Alfalfa: $7.45 per bale (and thats the good stuff...I must be lucky ) 60lb bales (5lbs twice a day)= $37.25 (5 bales)
SmartPak: $45 per month (joint and hoof/coat)
Feed Total: $115.25 per month...$1,383 per year (with no change in alfalfa/feed cost throughout the year...yeah right!)

Farrier: $70 per month when showing (front shoes only, aluminum)
$60 per month when not showing (front shoes only, steel)
Farrier Total: $780 per year (showing 6 months)...may be less or more depending

Vet (dundunduuun!): At school my vet suggested that I worm every 30 day because we have 20 horses sharing the same turnout pens and is exposed to the school's personal 60 horses (I thought about daily wormer, but I heard it does weird things when you take them off)...that being said...
Wormer: $10 per month=$120 per year
Vet Care (non emergency): $500 per year (coggins, shots, teeth (if needed))
Vet Care (emergency): $1000 per year...if not more! My guy got sick at school last year and had to stay at the vets for a week with an I.V. Can we say EXPENSIVE!
Vet Total: $1,620 (could also be more or less, but probably more!)

Grand Total: $5,223

I would say that's somewhere around where me and my horse peek every year as far as basics go. Not included are lessons ($40 per lesson x 4 or 5 a month), show bills (8 shows per year), show/grooming supplies, show clothes and tack. I show both western and english so clothes and tack are a big investment. I have found that buying good quality used tack that has a good re-sale value is smarter then buying everything new.