its a puppy scam! dont fall for it. i own a yorkie. what i can tell you is that a breeder CANNOT guarantee you what size the dog will be. standard yorkies are 5-7 lbs. but i have seen a yorkie (full blooded) that was 18 lbs. it just depends on the dog. also, there is no such thing as a teacup yorkie lol. that is just a sales gimmick. a responsible breeder will not only show you the pup before you buy it, but you can see the parents and the breeder should give you numbers of ppl she/he sold to-you can call them and see how the sale went, and ask about their dogs health (yorkies can develop genetic problems like shunts, and kneecaps that slide out of place when they walk, kidney failure etc).
dont but a puppy without seeing it-EVER. i suggest you get on a forum called yorkietalk.com. im a member there, and they give excellent breeder advice! you can also join it, and find a good breeder in your area! they also slam bad breeders and try to warn everyone about them.
theres a lady on there that did the same thing you were going to do. bought a dog without seeing it, it was shipped same day a long distance. the dog arrived in really bad shape, and they spent thousands on vet bills only to euthanize the puppy because she was only 5 weeks old and not even old enough to be weaned.
its a bad scam-dont fall for it.their plan is that you send them money, they promise to send the dog (NEVER DO!) and you are out the money and cant find them-suddenly their email and phone numbers dont work.. and you are sh#* out of luck, and the court system cant help you.