We actually did go through Costco for a new AC and heater about 3 years ago. We got several quotes and the Costco one was either the cheapest or 2nd cheapest quote (I can’t remember for sure—if it was second cheapest, it might have been a better brand). We also got a decent Costco shop card for going with them. I’m guessing it just varies depending on who your local Costco is dealing with. We have been satisfied with what we got.