For vet care I pay the following:
Teeth: 145.00 (US dollars)
Shots twice a year : 65.00/35.00
Worming: every two months ( 2 tubes = 15.00)
Farrier: 100.00 for a trim (I have a draft horse - regular size horses a trim can be 25.00-50.00 shoeing can be 35-75 or more).
Training: I pay 20 per lesson, but my trainer charges other clients up to 45.00 per hour lesson.
Tack: saddles, bridles, halters, leadropes, brushes, buckets, grooming supplies. I find a lot of this stuff on eBay and online stores. We also have a huge tack sale in our area twice a year where you can get amazing prices.
horse trailer: 2000-8000 depending on size and style. My boy outgrew his horse trailer a few years back and I never did buy a new one.
When interviewing for a boarding place ask what their experience is in dealing with horses, ask to see their feed, the stalls, the pastures, the other horses. Talk to other boarders. Take a look at several different places before you set your mind on one.
When it comes to buying this checklist is super intense on what to find out about the horse. And always get a vet check prior to buying. http://www.equinelegalsolutions.com/assets/HBC.pdf
Hope that helps!