I also bought my little girl with undocked tail. As everyone else has said, you have to pick the breeder first and discuss with them. I got Izzy (she is in my avatar and a parti Yorkie) from Greens Treasured Yorkies. (
Treasured Yorkies - Home). Brenda is a member here. We discussed it and she left Izzy's tail for us. Love Brenda, she is a great breeder. Izzy was so well socialized and almost completely pee pad trained when we brought her home almost a year ago. Good luck in your search!