"Redundant" is not the same as "wrong".

(To pick a nit on a nit.)

I don't regard that as correct. Cheap can mean multiple things. I can say this fabric has a cheap feel to it. This is a reference to quality. The shirt may have cost me $400, but the workmanship and materials that went into it were of low value. When you say you'll give me a full refund for the shirt but then only give me store credit, I could tell you that your words were cheap.

Yes, this relates back to price in the end, but having a cheap price means you paid a small amount for it. Having a cheap quality means it's worth a small amount, but you might have paid much more for it. Clarifying with the word price gives a very specific meaning. Cheap doesn't always imply price.