Hey Krista. Welcome to Yorkie Talk. I'm 21 and I'm finishing up my last year of college this year. I got Stewie in February and I am glad I waited as long as I did.
If I were you, I would wait until you have a place of your own and a plan for what would happen to your dog (who would watch him/her) if you wanted to go on vacation.
Yorkies are great companions, but they eat up a ton of time. I often have to pass on really fun invites to go out because I have no one to watch Stewie and I would never leave him alone all day and night.
If your parents were 100% accepting of getting a dog and were willing to take 50% if not more responsibility of it, I would say YES! Go for it! but since you are not exactly sure of them and how it would be with a dog in their house, I think you should wait at least a year until you have a feel for what college is really about and how your studies will be going. Then, tell your parents how well you have done in school and you would love to get a Yorkie as a family pet.
Anyway, I hope I helped.
P.S. to answer your questions about spending - I spent about $500 on Stewie alone (which is very inexpensive for a pet yorkie, as other people on this forum will tell you), plus supplies,Veterinary care and other fun stuff - the cost is through the roof. I don't buy anything for myself anymore
At least 40% of my income I spend on Stewie.