Part of that annual cost will be veternarian bills, shots, etc. Without regular vet visits you increase the chances your horse gets sick and dies from an illness (horses are like 5 year old humans, they get sick easily).
Another part will be whether you are shoeing your horses. Horse shoes are mandatory if you are riding your horse over any hard surfaces (pavement, rocks, etc). Without horse shoes the horse will hurt their feet on the hard surfaces, become lame, and it will cost you way more in veterinarian bills.
If on the other hand there are no hard roads, no rocky surfaces then you will be fine. This means you will need to think ahead when it comes to where you can ride your horse.
So yes, if you have lots of soft dirt for your horse to roam around on - large grassy fields, soft riding trails, etc - then absolutely, skipping horse shoes will be a possibility.
Which will save you time and money because horses need to be fitted for new horse shoes every couple of months.
Feeding your horse is not quite so onerous. You just need adequate foods that horses can eat - and you need to avoid anything that is potentially poisonous. Because otherwise your horse will eat it, get sick and die.
Basically the long and short of it is that caring for a horse is going to be a long and difficult process - which is why most horse owners choose to hire someone else to do it for them and have their horses stabled on a farm explicitly made for horse lovers. (Such horse farms are pricey however, just a warning. But at least they reduce stress.)
So before you think you can just go out there and buy an horse and use it for transportation or as a pet, think again. Do your research. Talk to horse owners. They are way more expensive to take care of than the actual cost of the animal.
