Welcome newbie. you have found the right place for all your answers here
we love pics so that is the next order of business
To your question in my opinion I would not pay more that 5oo for a non registered yorkie.I also live in michigan and there are some good breeders selling for 600 akc registered,with a year guarantee on life threatening defects and 6 mths for non life threatening problems.
BUT: essentially it is up to you what to charge for your pups no one can tell you that.you can always negotiate if you really like to perspective new owners. good luck what ever you decide