...but keep in mind that the inital price of the animal is NOTHING compared to what you'll spend on feeding it, and caring for it. Growing up, I always wanted a horse, and I'd be all excited when I'd find one for say $500, but then my dad would remind me of the extra hay and feed, and time spent caring for and cleaning it. And if you're not set up, you'll need shelter for it, a water source, somewhere to store feed, fencing...and someone able to do all of this. As well as be able to care for it when something is wrong, and be able to tell when something is wrong. I would spend some time around cows (or goats, although I'm mostly speaking about cows here, because that's what I have experience with) first to see what you're in for, if it's something that's totally new to you.
I'm in Canada, so the price info I have probably isn't too relevant to you! I really don't mean to sound negative at all, just trying to give you an idea of what to expect. I'd be happy to help out more if you'd like!
P.S. It sounds like you've got a wonderful opportunity though, so I would certainly give it a try (can you rent for a few months, and then decide to buy if you're enjoying it?)! Do you have any experience with homesteading or farming from before? If it's totally new to you, and you jump in feet first, you'll find it's a HUGE adjustment! Good luck!