Mike's PCjr Page

They are on eBay for between $60 and $80 usually. You are looking for the green-eyed Microsoft bus mouse. It looks like it has a 9 pin serial connector, but that's actually the bus version. (The serial version has 25 pins.)

Mine has the DB9 on the back.....
I saw a couple on ebay.... may have to bite the bullet....hard to justify just to put it in the drawer but I might...