Classic gear like Marantz, Mac and ARC. Try buying a pair of Marantz Model Nine amps, or a Model 7 pre-amp. Big bucks for sure. Take a look at what an ARC SP-3 goes for these days.
If we would have been smart enough to invest in, and stock pile these early editions back in the late 70's and early 80's, it would have been akin to collecting collector cars.
Frank