For the satisfaction of making the adaptor yourself try two searches for "USB pinout" and "PS2 pinout" both yielded different but desirable results. A good one was www.pinouts.ru/slots/USB_pinout.shtml
Soldering the part up from scraps might give a neater solution than the adaptor hanging out. And you could just try the office supply stores in town, but can you drive across town for three dollars in shipping. Office Depot is probably the best to try. Gotta watch those adaptors, put a serial gender changer in my pocket once and that is a dark tale.
Roger Van Arnam