Hum... A quick hack would be to solder a DB9 with wires inside a new controller. Just respect the pinout of each direction and buttons.
This is not optimal if you own a 10 button gamepad but... It's better than nothing.
The issue with bulding such a device is to emulate the host instead of the endpoint. USB joysticks are not equally made... This means that there would be a lot of incompatible device... 
I did this a few years ago with a Logitech Wingman gamepad. Soldered a DB-9 connector to it. I can use the Wingman on its own or plug in any old 9-pin joystick. Works great.
I think the Wingman was $2.99 from a Thrift store. The DB-9 connector I salvaged from some old piece of electronics.
