nos parts

what does everybody do when looking for parts? if it is a foot operated dimmer switch, you go to napa,az,oboys,aap or wherever. what if part is not made anymore? where do you go now? i see a lot of parts on web when browsing. some are really high dollar. a pair of tail light lenses for a 69-71 dodge truck 90 ea used 220/pair new nos. it makes my wallet hurt. useed is okay most of the time but what if used not readily avail? just curious where people go now.
You can also find many electrical parts thru Cole Hersee. They been providing reliable world class switching products to the automotive, marine and trucking industries since 1924. Other parts I find at swap meet's or shows like Carlisle.