Thumbs up on Costco, but they are a little limited on coffee bean selection. Starbucks is one of their high-end sellers. Never seen them carry an espresso bean blend, so never considered them for coffee.
Unless you go through 2 lb's+ a week, there's little benefit buying from Costco, as freshness trumps price when it comes to coffee. I like to buy beans from my local cafe as they are always fresh and never have to buy too much.