I don't know about a lot of them listed on the website, but there are a boat load of ones on Amazon.com, type "UTV Rear View Mirror" to search. I would think the Polaris one would be great quality....
The Polaris mirror on my RZR has taken a lot of abuse and is still functional.
"Abuse" includes quite a lot of dust being wiped off, with only a few scratches resulting, and me banging my helmet on the mirror due to really rough bumps without me wearing a harness, so I got pitched around inside the cab.
At one point I had to scrape some helmet paint off of the mirror.
In January when I had a rollover accident in my RZR (and was not wearing the harness), I actually popped the mirror's ball joint out of the socket with my head because I hit it so hard.
I'm still recovering from that accident, but the mirror just needed to be popped back into the socket.
So I believe that the Polaris mirror kit is worth $60.
If someone says the $20 one is low quality, then that seals the decision for me. Next time I'll buy the Polaris one again.
Too many times I've gone through several "cheaper" alternatives because I was unhappy about the price for something, only to end up hvaing spent just as much or more on cheaper stuff that didn't work out.