What obscure accessory did you trade in for way more than you expected?

I had a clear out this weekend and finally dragged an old box of random hardware into the glasgow sauchiehall street store. It was mostly just old ps3 controllers and a tangle of hdmi cables, but buried at the bottom was a gamecube broadband adapter. you know, that little block you needed 20 years ago to play phantasy star online on dial-up? completely useless now.

I figured it would go into the junk pile or maybe get me a fiver in store credit. the guy scans it and says, "right, that's £45 cash for the adapter."

I almost fell over. apparently, the scarcity has made them gold dust for retro collectors! It was easily the most profitable thing I traded in all day. Has anyone else had an absolutely bizarre piece of niche retro hardware or a forgotten accessory give them an unexpected cash windfall at cex? What's the most surprisingly valuable item you've ever traded in?