Don't Forget to look at Amazon frequently. I just got a 4 port system, with 2 aftermarket controllers, cords, and 2 joysticks (prob just use for Space Dungeon). I'm assured it all works. I paid $30.30, plus like 8 bucks for shipping. Seller was quick to respond. You have to find a person who wants to get it out of the house, but has a reasonable mind for price. Low prices move. So, check daily.
This is also Yard Sale season. I always find tons of good stuff. Good way to spend a morning. People just want to get rid of "crap", so it never hurts to haggle.
Good luck.