When I started collecting the consoles there wasn't as big a group grabbing these things up. So I got a lot of this stuff before it would have become really pricey. A friend of mine was collecting Atari 2600 Cartridges and we'd go into a lot of rummage stores like the Salvation Army and Goodwill. And I noticed there were a lot of pong systems in there among other odd ball machines. And so I started buying up what I could find. This was just before Ebay came along. Once Ebay dropped, it was all over for finding good stuff in rummage stores.
Although now with their prices skyrocketing, folks might not find as much value in selling these things through their service and they'll once again show up in rummage lots. Probably take a few more years.
K