The Dreamcast is one of the best consoles to date in my mind. I would think you could get one for $30-$40 without any games, but at flea markets around here they tend to go for $40 for a core system with one controller. I can't stress enough how great this console is though. It has the most ports of Capcom and SNK games of any other console, and they are all pretty much arcade perfect ports, but with better sound. There is KOF Evolution, KOF 2001, KOF 2002, Garou MOTW, Street Fighter Alpha 3, Power Stone, Capcom vs SNK 2000, Capcom vs SNK 2, Star Gladiator, Last Blade 2, Vampire Chronicles, Street Fighter 2X, and Super Puzzle Fighter X
You get a lot of shooters that are well done..Ikaruga, Mars Matrix, Gunbird, Cannon Spike, Twinkle Star Sprites, Rainbow Cotton, Zero Gunner 2, Castle Of Shikigami, Rez, Chaos Field, and lastly the amazing Last Hope: Pink Bullets.
There are also system classics that define the console, such as Shemue, Seaman, Sonic Adventure, Space Channel 5, Jet Set Radio, Chu Chu Rocket, and Resident Evil Code Veronica.
Then you have Firepro Wrestling D... the holy grail of Firepro games, and wrestling games in general.
Also you have to factor in the Dreamcast's ability to play homebrew games, applications, and emulators as well.