I gave away my Gameboy color with Pokemon Blue Version to my cousin, just like my Nintendo 64 with Super Mario 64 and WWF No Mercy. When I asked them back borrowed, they told me they couldn't find anymore. I regret it dearly.

I sold my Wii collection at Gamestop a some time ago. I got about $350 for it and I used it to get a Wii U. The cashier was kinda pissed though which I don't know why. She said, "The only reason why you're getting this amount is because they're all Nintendo games". Which I guess she's right but she had an attitude.

I also had 2 copies of Skies of Arcadia Legends and sold them a while ago for peanuts. Now they're worth 80$ per CIB copy.

I regret selling my Pikachu Gameboy. ;/

Had it when I was super young, but I forgot who I sold it to. Sold it for only like 40 bucks lmao

I'm currently doing that with my Wii/Wii U games to get an NX and games for it next year (Yeah, kinda crazy to do that when we don't even know what the thing is, but I would end up buying it anyways so might as well take the risk and save some cash lol). Hopefully I won't regret it later.

Yeah, I was around 10 when I did it and had no other way of getting money to buy new games, so I had no other choice.

Honestly you should hold on to all of your WiiU stuff as that's going to have the most collectible games of any console in the last 15+ years. 

I sold many of my N64 games to help buy a PS2, and I regret it to this day. It's because of that I rarely ever sell my games.

I had to get rid of my SNES when I was about 14 or 15. It was painful, but it had to happen. Thank God for the Virtual Console!

I sold PS3, PS4, X360, XONE consoles & all huge unplayed library PS3 & X360 games after graduation of college, because i was complete jobless for like 3 months until they hired me, and another bad news, i had to wait for 1st salary in like 2 months, so, i sold my most expensive console & 10 games, Neo Geo AVS... Yep, i actually sold them year ago.

Finally, this year, i brought them back, except for the XONE & Neo Geo AVS.

My parents only let me get new systems if I agreed to give my older ones to less fortunate relatives in Vietnam. I lost both my NES and SNES in this way :(

Sucks but at the same time I'm glad I was able to give it to others who had much less than I did.