Sigh, I think this is partially what has pulled me away from the hobby. When I was collecting hardcore about 10 years ago I could pull in some pretty amazing stuff for very little money. I was always shopping at this one flea market (Lynn MA) where most of the sellers were the guys who cleaned out foreclosed and abandoned properties. That place regularly produced dusty boxfuls of classic gaming goodness. Back then the sellers were more interested in quick money than researching their wares. I hit that same place on the way to the beach a few months ago and it was nothing but xbox and later stuff at near gamestop prices. I guess if I was there every weekend like I used to be I might still catch a box of intellivision games, but then again it's been 30+ years since those games saw the light of day so there's just not that much left to resurface on the used market.
Without that adrenaline rush, collection list check-off, shelving pride, online bragging and initial test play there isn't much to keep a person collecting. Even if I do find something odds are I already have since my collection is pretty vast. Once in a great while though I still find something, just two weeks ago I scored at Mattel Electronics Horoscope Computer for $2 at Savers, and since it's one of the harder Mattel handhelds to score I briefly had that little rush.