These four consoles are by far the cheapest to buy and easiest to collect for. If you want to collect for Studio II, Astrocade, Channel F, Arcadia 2001 (Why are there so many of these?), APF-MP1000, Creativision, Adventure Vision, 5200(?), or vectrex (Sadly) you are a bit crazy perhaps.
I'm looking at the Wikipedia page for second generation consoles... Why are there so many?!? No wonder the market crashed There were like... 18 different consoles worldwide... and that's just silly.