Raphnet is even more expensive than RetroUSB.
EDIT: However the GameCube to N64 adaptor is very interesting... Considering purchasing it. Very good idea 
I disagree. with a 4nes4snes, you can use up to 4 controller ports with one usb cord and a 20 dollar chip. There is no way retrousb is cheaprer if you are using more than one controller.
Same goes for Genesis and SMS because you can get a db9 chip with a multitap and hook four up that way.
As for the rest of the systems, raphnet and retrousb are similar priced.
Forgot to mention, if you are doing a N64 to USB, use the may flash adapters. You get 2 n64 ports for about 20 bucks.