In the late 90's I had a massive Tandy Color Computer collection - massive hardware wise anyway. I had the monitors and disk drives which are very expensive now and hard to find. Fortunately I have more actual coco computers than I did back then (especially coco 3's) and a crap load more of the carts since I had mostly disks back then. Still I had a lot of boxed disk games that I sold for almost nothing when ebay was new and not many coco collectors seemed to be around.

I also regret getting rid of my sega power base converter a couple of years ago because my SMS seems to be on the fritz. I figured I didn't need the PBC with having an actual machine but now I wish I still had it. Miss playing Rampage on the SMS, love that port.

Most of the other things I've regretted getting rid of, I've reacquired over time so as long as I don't repeat the mistakes of the past, I'm golden