If you have one reason for wanting this dog - because they are "adorable" then please, please don't get a dog. Too many puppies and dogs end up abandoned and at the pound because someone thought they were adorable, then they grew up and developed issues the ignorant owner could not cope with.
You seem to have done no research about this breed or type of dog. Teacup dogs are a myth. They are usually dogs with health problems because of their tiny size.
If you have good reasons to want a dog other than you think they are adorable, then ask yourself the following:
If you get a puppy, are you prepared for the time it will take to toilet train it.
Will you hav time and money to train your dog and socialise it (go to obedience class)?
Do you have enough income to pay for the dog? Training, good quality food, toys, vets bills, registration, dog accessories etc. (If your parents have to pay for the dog, please do not get one. What will happen to the dog when you leave home? Wait til you are older and in a stable situation please.)
Will you have time to exercise your dog sufficiently (an hour a day depending on the size of dog.)
Do you have a house suitable for a dog? If you have to move, will you be able to take the dog with you?
How often will you have to leave your dog alone, and for how long?
Are you prepared to take on the responsibility of being pack leader to an animal that needs a lot of looking after? This is not a doll, or a fashion accessory, it is a real life being that can suffer if not cared for properly.
If you really feel you know what you are getting yourself into (and if you have not previously owned a dog, or have not researched how to care for a dog yet, then you do not know what you are getting yourself into!) then by all means, get a dog, but only by from a reputable breeder, or adopt fro ma pound. (If you adopt from a pound, make sure you know what to look for in a dog, and if you have any reason to think you might not be sure, take a dog behaviourist with you to help you pick out a dog that is right your you home, financial situation and lifestyle.
Owning a dog is a joy and a privilege, but too many people just do not understand what a huge responsibility it is until lit is too late and they realise they cannot cope.
Good luck! Here is some reading for you:
http://www.doginfomat.com/b4ugetadog.htm
http://talkwhatever.com/showthread.php?t=5179
http://www.dogbreedinfo.com/beforeyoubuy.htm
http://www.dogplay.com/GettingDog/puppy.html
http://www.veterinarypartner.com/Content.plx?P=A&A=302
http://www.xomba.com/10_things_you_should_know_before_buying_puppydog