You won't find a yorkie from a reputable breeder for $300. In fact it would be hard to find one for less than $1000 from a reputable breeder.
If you have money for vet bills and the care of a yorkie you should look into rescuing a yorkie. Other than that you will just have to save up money to get one. But there are a lot of adorable yorkie rescues out there who are in need of homes. Just make sure you get them from a reputable shelter or organization.
Here are some yorkies rescues looking for good homes in the Florida area.
http://search.petfinder.com/search/s...ip=Tampa%2C+FL
There are a lot of them and the adoption fee is usually around $200-$300. You have to send in an application to see if you will be approved to adopt.
Good luck with your search!!