Gazelle was one of the ads that recently popped up here; I was curious to see if they'd even acknowledge the ol' TG-16, and was pleasantly surprised when I moseyed on over. They must have a Turbofan working there, as they'll pay more for a TG-16 than anything else I checked (good condition with ac adapter, cables, controller):
TG-16 - $31
AES - $28
NES - worthless
SNES - worthless
N64 - $5
Gamecube - worthless
SMS - worthless
Genesis - worthless
Saturn - worthless
Dreamcast - worthless
3DO - $8
PS1 - worthless
PS2 - $5
Xbox - $5
P.S. - I'm not recommending this company or anything, as I've never heard of 'em before.