Clicky fever is indeed upon us. It's not hard to find a used one of these, but it is hard to find a clean one, so you'll need to break out the elbow grease. I've found instructions for cleaning the big version, but I haven't found any yet for the M2, which is the smaller version I'm using here. I like this one a lot better, as it has all necessary keys, but is much more compact.
After you read this guide, you'll be able to fully clean an M2 keyboard, so when you find one for sale at a garage sale for $5 you can say, "Yeah, but all those stains..." and take it away for $2, knowing that only a couple hours' work later you'll have a like-new M2! Yeah!
For those wondering, today's keyboard is part number 1395300, manufactured in Feb of 1994. There are no detachable keycaps or drainage channels.
For those with no idea what this is about, the Model M and M2 are keyboards that use a buckling spring mechanism in each key to provide tactile and auditory feedback. When each spring buckles it makes a click, resulting in a machine-gun stacatto of clicky noise, as my wife can tell you. She's sitting two rooms away. Read more here:http://www.clickykeyboards.com/index.cfm