There is a thread at the top that lists sites where you can buy anything you want. It depends on the amount you wish to spend as to which site you would prefer to use.
Buy harnesses, not collars, in order to protect your new yorkie's trachea from being damaged. OK?
Here are some harnesses I recently purchased from Joy at ******************.com
http://www.yorkietalk.com/forums/showthread.php?t=18612