just my $.02 worth...
all 'other' things being equal (interior condition, mileage, paint, road-wothiness, etc.), here are a few things to consider:
If you are comfortable with tuning a carb, the '80 is the last non-computerized C3 (I believe), and also lacks a lock-up torque converter;
The '81 Corvette had a computer running 'some' functions (ignition timing?), and an ' '81-only' THM350C, with a lock-up converter in the transmission. '81 also offered a 305 CID for California
The '82 is the 'last-of-the-breed', but came with a 4-speed, A/OD transmission with lock-up converter, controlled by a computer, which also runs the '82 & '84-only Cross-Fire Injection induction system.
If you're comfy playing with EFI, you may enjoy the '82; other-wise, you might want to choose the '80-'81 models.
The '80 models offered the last L-82s, all with automatic transmissions.
The '81 & '82 models offered a fairly rare two-tone paint option (D84?), which could prove to be of value in future years.
'82 also offered the first of many Collector Editions to follow ('88, '96, etc.). The '82 C.E. offered unique wheels, and the ONLY C3 having a 'hatch' back window, increasing it's value, too.
Happy Shark-hunting!!!