3. HP-75 calculator
Original price in 1982 (model C): $995 (price in today’s dollars: $2,282)
Buy it now on eBay (model C) for: $199.99
If the GRiD is a little out of your price range, but you still want some vintage 1982 computing power that you can carry around with you, how about an HP-75 calculator? They can be programmed in BASIC and have 16kB of RAM/48kB of ROM (with expansion ports for both). They came in two models, the C and the D, with the latter including a wand port for a barcode reader.
I didn’t have an HP-75, but I did get an HP-15C scientific calculator when I went off to college in 1987, which I still have... somewhere.