Like a lot of us on here, I have a vibration tumbler. Generally if a part can be buffed I prefer to do that than tumble the parts...However, I love to recycle 44/47 sockets off old playfields....These clean up very well in the vibration tumbler.. Once cleaned I solder all the bases and store them for future playfields swaps where I discard 555 sockets and replace with 44/47's.

I agree that PBR is the best place to buy sockets....However, for the standard playfield feature light socket, check these out...

http://www.allelectronics.com/make-a-store/item/ls-9/mini-bayonet-base-lamp-socket/1.html

$0.35 each