Well, you have an SMS yeah? I suggest you sell it to me and get yourself a Genesis v1 or v2 as stated here:
The reason is because the Genesis is backwards compat with SMS games, as well as supports Genesis, 32x, CD and has better controllers and standard composite output.Originally Posted by http://atariage.com/forums/topic/240554-which-sega-master-system-flash-cart-should-i-get/?p=3278364
Of course you'll be paying out the ass for any one of the Everdrive carts. Krikzz's site will offer his trusted suppliers of everdrives.