What I'm wondering, is if the person selling this was the original owner. Could it be something he found moving into a house, from a relative who moved away, died, etc?
Seems odd, with the titles there, that a person who was into the TG-16 would dump it all for so cheap. That is, unless this was the last system he ever owned, and didn't keep up with anything like it after that.
I saw similar about... 2006? I went to a large outdoor yard sale / flea market to look around. Someone had a lot of Dreamcast out, 12 games or so, system looked clean, etc. The guy only wanted $20 or $30 for it. I asked him what the story was with it, and he said he had it while he was in college, played it while at college, and after that, hadn't touched it. I wasn't interested, but tempted at the price, and during my talk with the person selling the lot, another person walked by, asked how much, and bought it on the spot.
That's a bit different though, as the Dreamcast was only about 7 years old at that point, whereas that TG-16 lot that buyer picked up is about 20 years old.
Who knows what the story is with the lot that guy got, all I know is $120 is a steal. It reminds me of some auctions I noticed on ebay years ago. A bunch of video game stuff, a lot of it TG-16, went up for sale, when a wife was cleaning out a lot of stuff from her dead husband. She typed that in the description for some of the things she was selling. However, she had more sense to put it on ebay, than goodwill it or similar.