Bed, Bath, & Beyond sells Atari systems now. Not sure if they have games integrated or they play cartridges. I know there are systems that play both NES and Genesis cartridges.
I never played Knuckles Chaotix.
Walmart around christmas had those systems for about $18. It was the Sega Genesis that plays carts, but also had 50 built in games.
They also was selling the colecovision but even though the controllers looked like the original and had the sleeves, you could plug the real controllers into the port and the controllers that came with it felt cheap, think that had 60 games.
Well when I went back to find them to see if they went on clearance, they were priced at $35 or something. Oh well...