I just replied to your pm (before reading this) so, my suggestion would be to go visit the Yorkie first, see if you think you want to adopt this little one.
If you decide you do, then I would suggest that YOU take care of the veterinary care...vaccination, spay/neuter, etc...after all you will want to do this anyway when getting a new addition to your family.
If cost is a concern...reconsider adopting as Yorkie's can be a financial handful as so many of us know!
Good luck on your visit tomorrow and please feel free to pm me if you have any questions!