Nowadays I tell potential customers right up front if it gets brought up, if price is the only thing that matters then we are probably not the best shop for you. I see so often, new shops that find or hear or whatever that many places charge per SF and find out what other shops charge but then fail to consider that the per SF price is based on the material that comes off the roll, not necessarily what the customer gets. They fail to account for the waste and all and price it based on the SF of actual material being installed.
Or as mentioned, I might ask to see a copy of the quote they got so I can be sure we are comparing the same materials, etc.