PSA: That $45 'uv filter' from the camera shop in Boise saved my 50mm, but the $12 one from the flea market almost cost me a lens | Analog Camera Club - Librear
Wait, I don't think the price is really what saved your lens though. A UV filter is just a piece of glass either way, so what matters is whether it's actually made of good glass and coated right. A cheap filter can crack or scratch just as easy as an expensive one, it's more about the coating and how clear it is.