Welcome Naomi! You have come to the right place for really excellent advice and support. I don't know what I would do without the advice and knowledge I find at Yorkie Talk.
I totally agree about NOT buying a pup from pet store. There are some great breeders on this website from whom you can get advice or maybe a recommendation of a breeder in your area.
Be careful of the so called "teacups", as they say above. If you do your research, you will discover the related health risks (not to mention vet bills.) These tinies are adorable looking, but carry potentially heavy health/nutrition problems and need constat care. I would certainly not recommend taking a teeny weeny to college with you. One stomp of a crazed freshman sneaker, and your baby could have severe injury.
As for grooming, my Mom has always kept her Yorkie trimmed into an adorable "puppy" cut, whick keeps the coat shorter and therefore easier to take care of as regards matting/knotting etc. My own Spanky has hers long, but needs diligent brushing at the very least, every 24-48 hours.
Good luck with your search; let us know what you decide and post pictures of your new baby when it arrives home.