I metioned a steampunk keyboard [1] a few months ago, and now, it looks like someone is actually making and selling them [2] (link via shadesong [3]). But even though these are made with modern USB (Universal Serial Bus) keyboards and not an IBM Model M [4] like the original, it's probably still in the “if you have to ask, you can't afford it” range.
Ah well …
[2] http://datamancer.net/vonslattkeyboard/vonslattkeyboard.htm
[3] http://shadesong.livejournal.com/3253978.html