Sega · 1989
Sega's 16-bit console reached a few shops in New York and Los Angeles in August 1989 and launched across North America that September. Inside is a Motorola 68000 at 7.6 MHz, with a Z80 driving the Yamaha YM2612 FM sound chip. Altered Beast came in the box until Sonic the Hedgehog replaced it in 1991, and Sega kept adding to it with the Sega CD, the 32X and a six-button pad. The smaller Model 2 arrived in 1993, Sega had stopped making the system by June 1997, and Majesco brought out the Genesis 3 in 1998. Counting the Mega Drive, it sold 30.75 million units worldwide. For a buyer, the questions are which model and board you're getting, which cables fit it, and whether the right power supply comes along.
6 models we cover.

Sega Genesis
Console$75–$150 typical ask
76 on eBay
Sega Genesis
Console$55–$110 typical ask
118 on eBay
Sega Genesis
Controller$25–$40 typical ask
93 on eBay
Sega Genesis
Game$35–$65 typical ask
153 on eBay
Sega Genesis
Game$100–$300 typical ask
22 on eBay
Sega Genesis
Add-on$210–$340 typical ask
41 on eBay