Chevy stuff - An underdash accessory tissue dispensor with the original box from the late '50s - $5.00 (yup, five bucks!). Traded it a couple of years later straight up for a set of new Chevy 2.02 iron heads, complete and ready to go, plus a set of Offy aluminum finned valve covers for them. Not a bad swap!
Non-Chevy stuff - At an estate sale in Kansas, a collector had tons of AMC, Hudson, and Nash stuff, plus a sprinkling of Chevy and Mopar items. Bought a factory Hudson windshield visor, complete with brackets and hardware, for three dollars (I sold it later for $300.00). Bought a complete '66 Charger rear taillight assembly for $25.00 and sold it later for $400.00.