glad u got your rollei back -- that's the biggie, and you are doing the right thing to reimburse the guy his $20 -- what the heck, small price to pay. Karma will smile on you.
to those saying he should be brought up on charges of receiving, or should have smelled something -- ease up -- if I found a rollei for $20 at a yard sale I'd probably plunk down the double sawbuck too -- it's an instinctive thing.
in this case, the guy did the right thing, cut him some slack.
as to whether yu should be criticized for leaving the stuff in ur car -- up to you, but in this day and age -- sorry if this feels like criticism -- but you really are asking for trouble if you leave stuff in a car. Nobody wants to live in a fortress world, but welcome to reality.