Broken microphone - now what?

I’ve got an iPhone X that isn’t eligible to be replaced without penalty until next December (it’s also outside the 1 year warranty by a couple months)....

I've always had difficulty having people hear me clearly when I make a call. I’ve dropped into my local Apple store a few times asking about antena/cell coverage issues to see if could get a lead on a possible solution. Each time the sales people have been eager to help and offered solutions like cleaning out the mic port, suggesting resetting network settings and checking bars when making a call, etc. But no one ever advised making a Genius Bar appt to check the hardware. I thought about making an appointment myself over the holidays cuz the problem seemed to be getting worse but they’re always so busy. Well, the other day I dropped into an Apple store in Palo Alto and they had a Genius Bar appt available right away and the diagnosis showed that my mic doesn’t work properly and the only fix is to replace the iPhone.

So, my question (I know, finally)...

What's the smartest (cheapest) way to replace a (defective (also with a slightly damaged screen)) iPhone that’s out of warranty?

Do I have to throw it away and pony up for a full priced phone?