Here is a list of systems to get you started. If you never played a classic game, I reccomend you order one of these systems from amazon or ebay, and research the games and order one of those. You won't be dissapointed if you play a system from the 90's, but a system from the 80's or 70's may frustrate some people, mainly because of the "bad graphics" (They were good at the time) or "primitive games" (Also good at the time. Well, some of them, anyway.) Some people don't appreciate classic games.
Anyway, here's a list of the most known retro systems.
Nintendo:
NES (Nintendo Entertainment System)
SNES (Super Nintendo Entertainment System)
Famicom (Japanese NES)
Super Famicom (Japanese SNES)
Gameboy
Gameboy Color
N64
Sega
Sega Master System
Sega Genesis
Sega Saturn
Segas Gamegear
Sega Dreamcast
Atari:
Atari 2600
Atari 5200
Atari 7800
Atari Jaguar
There are many more retro systems. Here, I've just listed a few.
If you would like to know more about these systems, or about their games or current prices, you can google it. You can find these systems and most of their games and online retailers like Amazon or Ebay. They'll probably not appear right off the bat, sometimes it takes searching in the search box to find them.
If you have any questions (I doubt you will, I basically just gave you the answers!) PM me,
NintendoGamr123.