I think its awsome that you want to learn about horses. I would suggest that if you are unable to volunteer around at nearby barns, that you get books and read into horses. I would also call around to nearby ranchs (if there is any in your area) and see if they offer riding lessons. Riding lessons cost between $20 to $50 an hour (sometimes more than an hour). I think its great that you want to eventually buy a horse, but what I was always told is "wait a year, build up your knowledge, build up your experience, and then way your finances and if you can buy a horse, then go for it!"..
When someone asks me, how much do horses cost? I always say "Its not so much the buying, but the keepin"
GOOD LUCK IN YOUR JOURNEY TO BE A HORSEWOMEN!