Where can they purchased. Which models, pricing. Aimpoint says they dont refurbish. They say that they work or they are destroyed. We all know this is bull. So where can I did one up.
We all know this is bull.
We do? 
How did we find out?
Aimpoint does not sell refurbed Aimpoints.
C4
That’s easy…
Go to any gun show and you will find a guy selling one, right next to his supply of Beef Jerky…
I think the only thing you’ll be able to get other than new is used.
I would say that they do cut them apart (and or chrush them) and see what failed. I sent a ML2 in that had beed damaged thinking if they could fix it, good, but if not I would just buy a new one. Aimpoint replaced it. They did call and ask if they could replace it with the same one or did I want to upgrade. Total cost to me? $5.95.
Aimpoint does not sell any refurbished sights, period.
I buy used Aimpoints exclusively (exception, LaRue’s Poor Boy Specials.) Sorry, Grant. 
If an original purchaser has a problem, Aimpoint fixes it. So there are virtually no problems on used Aimpoints. Real ones anyway.
When folks want to upgrade, Harv and I are there to help.