I have a "boom PSX+N64 USB CONVERTER" from lik-sang that works perfectly with Bannister's emulators with no additional software. I don't know about MAME.
I think it was about $12, I bought it a few years ago.
The only downside it that it only works with one controller at a time. I used to have a JoyPort ADB which let you plug in four controllers simultaneously, and had nice software to set up everything.