why not building one? the first posts i ever made were about that.
it took me some time but i've connected 2 mega/sega genesis 1 and 1 sega genesis 2 to 32x and a cdx to a 32x and they all work fine.
1. get pinouts for mega/sega genesis 1 and 32 x at gamesx.com
2. buy solid core wire (insulated would be better) thin enough to
plug in the 32x mini din connection (you need to peel the
insulation just to plug the wire in the conecction 6 milimeters
would be fine, both sides)
3. cut 7 wires 10 to 11 centimeters long, plug them one on one
using the pinouts as a guide to keep them in place use a
silicone gun. (genesis 2 to 32x connection).
to plug on the genesis 1 you will need a male din connector
and solder the tip of the solid core
wire or just plug the wine inside the hole of the din female
and solder the tip directly to the board of the console.
4. if you connect port (+5 v) mega/sega genesis 1/2 to 32x is
possible to use only the power adaptor for the mega/sega
genesis 1/2 to power both the console and the ad on.
some people say it will fry your power source but i use to
play 5 hour sessions 4 days a week and my setting works fine.
this will be more fun and easier than buying a connector.