have you thought about getting a rescue yorkie?
i have 3 yorkies and one of mine is a rescue, shes the best well behaved dog i have, shes never been ill in the year and a half that i have had her.
if you ring around some of the rescues in your area they will phone you when a yorkie comes in.
ive had male and female yorkies and would say there is not much of a difference with them.
ive had 2 males together, 2 females together and a female and male together but i would say most of the time a female and a male gets on best.
i help out on a site called
www.alfieslostterriers.com and they have a rescue rehoming forum and sometimes have yorkies on there.