A new console is being released soon - it's called the RetroN 5 by Hyperkin. It allows you to play 5 different cart types, which in turn allow you to play Japanese, European, and American versions of all of your old games from Game Boy, Game Boy Color, Game Boy Advance, Genesis, Mega Drive, NES, Famicom, SNES, and Super Famicom. All in one system!
The RetroN 5 was just announced on Amazon as available for preorder, here.
The RetroN 5 is $100 and it's releasing on Halloween (Oct 31). Although the system supports 2 wired controller, it also supports a Bluetooth controller designed for the sytem! The system is full HD as well- it has an HDMI port, and plays games at 720p resolution.
Yes, there have been a ton of retro-cart systems out there, like the FC Twin, but the RetroN 5 looks to be the most complete setup available.