I wanted a yorkie when I was between 18 and 19 years old...I just got one this year and I'm 35. Yes, they are expensive but they are definately worth it. Start saving, it'll be good for you
Remember, don't be scammed by the cheaper yorkies you see online. If it sounds too good to be true, it is. A reputable breeder will not give you a yorkie because you really want one and can't afford to pay what they're costing(beware of one that will). Also, if it sounds too expensive for the norm, watch out for that also(they should not be $5,000-$8,000 for pet quality).
There are lots of costs with owning any dog, and it's totally worth it to take an obedience class with your new puppy when you get it. Start with a change jar and put any extra cash you have in it. Skip an extra fast food meal or use your bottle return money to just throw in there. It may take awhile but it really should because a pet can live 15 years. Good luck in your savings and search.