My best is probably an Olympus RC, RD and SP for $3 each. The RD and SP both need a CLA though so this will be a quite expensive little 'best find'. I'm really excited about the RD as I'd been looking for one for months after finding a DC.
Fortunately I also picked up a dozen other cameras - including a dead Contax IIIa and a small herd for Canonet 17s - for $3 each as well. Hopefully selling those, I'll manage to break even in the end.