Another good place to visit on the web is
Dog Food Reviews and Ratings | Dog Food Advisor
Check to find what food interests you, then, you can look up that food and do the store locator so you can find a source close to you.
I would get that puppy off Purina ASAP. As small as Yorkies are and as tiny as their stomachs are, there is no reason to fill it full of junk and fillers. Small dogs need good quality food more than larger dogs IMHO since they can only take in a limited amount of food. (and NO, I feed my big dogs high quality food, too - they actually work and don't have room to fit junk either)
Oh! I just looked up Purina Puppy Chow - 1 star. Only 1 star. Blech! Yes, please put your baby on something better.