My boston terrier and Pit Bull eat Solid Gold dry dog food, the dark blue bag. It's straightforward on the tummy and makes their coat shiny and soft! I started using it because it was what the breeder of my pit was feed all their dogs. i liked it so much that i started giving it to my boston. its not the cheapest...its one of the more expensive foods, but you get what you pay envelope for. It is a very good dog food. I get it at Petco or PetZoo.
There is NO high quality food surrounded by Petco that ISN'T thru the roof, if you want high quality you are going to compensate for it. the cheapest high quality food I've found is Taste of the Wild ($44 for 30lb bag) but not sold at petco. Only thing I can propose is Solid Gold or Wellness Core, both sold at Petco.
Also Petco sells Frontline in their store, your best bet is Frontline Plus which I don't believe they carry. Stick to Frontline Plus it's the best one out in attendance.
Answers: The two that I believe PetCo carry that are quality are Wellness and Solid Gold. If your dogs are adults, I would try Solid Gold 'Just a Wee Bit' for starters.
My brother raise Shelties and swears by Solid Gold, my parents have started feeding it to their toy poodles but I have a German Shepherd, and the 33lbs pod of food is 50lbs, I'd probably have to buy two of those per month.