The price/cost of a horse depends on many factors.
Would you board or do you have your own property? If you board, what does it include? Some places have "full" board, where everything is included, some places have "rough" or "pasture" board where you have to come and clean your own stall and feed/water/hay your own horses. Prices are also dependant on what part of the country you live in.
It costs less to worm yourself and give your own vaccinations. You can do most yourself. Rabies must be done by a vet. (we buy our vaccines and wormers off the internet, buying in bulk saves you money too.)
There's also hoofcare. My daughter has an equine degree and has learned how to trim the horses feet herself. For any shoeing, or correctional trims, we pay a farrier. A trim costs anywhere from $20 - $50 again, depending on the area.
If you are able to do simple first aid care, (I'm a nurse, so I do all the simple stuff) that will save money.
Do you know anyone with a trailer you can borrow in an emergency? Buying your own trailer is another expense. Many people do without. If you don't know someone, you'll have to pay for a "farm call" from your vet. Anywhere from $50-$150 + whatever was done to your horse.
I'm not trying to talk you out of a horse. We are breeders, so give me a call!
But there are several things you want to think about before you jump in, so to speak. I hope I've helped.