About the best you're going to be able to do is one that does the following combinations:
-PS1/2, Dreamcast, Gamecube
-PS1/2, Dreamcast, Saturn
-PS1/2, N64
All of the other available adapters for retro systems are solo units.
Then of course, there's
http://www.retrousb.com/, which sells USB conversions of existing controllers and the kits to do them yourself. Then of course, there's always putting in a little elbow grease, adapting the controllers to the parallel port yourself.
So, it's either plunk down the cash or become a do-it-yourselfer.