Those of us who had that stuff probably got rid of it years ago.
Another option is a place that recycles computers and electronics. You may need to be near a decently sized urban area to find one (check a phone book or ask at a local computer store, or the state environmental department). If you lived up here I could point you to several places that sell this kind of old equipment for the price of dirt. Recycling scrap electronics is big (well, medium) business.
Yet another option is to use a modern keyboard and mouse with adapters for the old connectors. Like the following:
http://www.cablesnmor.com/mouse-adapter.html
http://www.cablesnmor.com/keyboard-adapter.html
Note I've never dealt with this company so I'm not necessarily recommending them, just showing you these pictures so you can see what they look like.