Can I pay $100 for a horse every month?

You can never have a certain cost a month, if grain is 15$ a month I would NOT go with that grain.. I would say mimium $200 a month. Vet calls are usually $50-100$ just to get the vet out. Then you can add the shots , you need the immunization , and the flu shots too. Farrier is usually $80 not 25$ and I really don't think $2 is a good quality bale of hay, you could find a good horse to lease for $100 and you won't have to wprry about vet and all that