Here's a list of mechanical keyboards. They typically start at $70. Ergonomic ones with fancy shapes usually starts at $200. (If you don't know what Cherry MX means, first see: Guide to Computer Keyboard Key Switch Mechanisms.)
Truly Ergonomic Keyboard (Cherry MX Brown)
(Topre switch) μTRON Keyboard (hard to buy in USA)
(Cherry MX Brown) Kinesis Contoured Keyboard
• Maltron Keyboard (your choice of Cherry MX)
(may be hard to buy) Picture at Ergonomic Keyboards Gallery
(Cherry MX Brown) Logitech Gaming Keyboards
(Cherry MX Red) Corsair K60, K90
All Cherry MX switch types, including {Brown, Black, Blue, Red}. Many different models, with or without number keypad. Be sure to read model's spec in detail. 〔☛ review of Filco Majestouch keyboards〕
(Cherry MX Blue) amazon 〔☛ Gaming Keyboards: Levetron, BlackWidow, Sidewinder〕
(Cherry MX Blue) 〔☛ Cooler Master keyboard review〕
(White Alps Strongman switch). amazon This keyboard has strong presence in Mac community.
(Cherry MX Black) amazon
(Cherry MX Black) 〔☛ Gaming Keyboards: Levetron, BlackWidow, Sidewinder〕
(Cherry MX Blue) Some models are not mechanical. Be sure to check spec. 〔☛ Das Keyboard review〕
(may be hard to buy in USA) 〔☛ KBC Poker Keyboard, Ducky Keyboard〕
(may be hard to buy in USA) Different types of Cherry MX switches available. 〔☛ KBC Poker Keyboard, Ducky Keyboard〕
(buckling spring) IBM Model M keyboard, Unicomp
(Topre switch, professional model only) 〔☛ Happy Hacking Keyboard Review〕
Adesso Full Size Mechanical Gaming Keyboard with USB Hub and Audio Jack - USB and PS/2 (MKB-135B) Adesso MKB-135B Pro. Switch Type: Cherry MX Blue. amazon
wired - Black - English - US http://www.cherrycorp.com/english/keyboards/Office/G80_3000_MX/index.htm amazon