Arpie Needs Help w/Mattress Buy

Arpie: Okay folks, I need help. My wife and I are heading out mattress shopping. I view the mattress business a step below used car sellers. For me it’s even tougher than buying a car because I know nothing about the lingo or construction of mattresses. I have heard some say that I must buy a new box spring at the same time and others that say it’s just a scam to double the profit. Does anyone have any thoughts on how I should proceed without being ripped off? We’re looking for a queen size semi firm mattress.

Question: What recommendations/cautions can you offer Arpie re: the purchase of a new mattress?