Amazon and Ebay are your friends.
http://www.tedweber.com/https://tubedepot.com/http://www.angela.com/https://www.tubesandmore.com/http://www.mouser.com/Maybe something here, not sure:
http://www.ax84.com/http://www.digikey.com/?&WT.srch=1http://www.mojotone.com/https://www.amplifiedparts.com/ I've been pleased with Weber, Mojotone, Mouser, and have used most of the others. Mouser for bulk parts or stuff the others don't have.
Local pawn shop may have a DMM. Cords from hair dryers and other things are cheap at thrift stores... and you may find other things you need at thrift stores, yo never know what you might find there.
Good luck. We still have a RS but they never seem to have what I need. They made some great stereo systems back in the mid to late 70s. Remember the MACH I II and III speakers. They were pretty cool. I had a RS integrated amp and tuner in the 70s and it rocked!! ...but I drift.
J