I've used the Cooler Master Quickfire at my old job which made me fall in love with mechanical keyboards. After leaving the job (and the keyboard) behind, I decided to spend more time looking a keyboard that would fit my needs. The options are certainly plentiful but I ultimately ended up buying a Ducky Shine 3 with Cherry MX Blue switches.
I absolutely love this keyboard, and if you look past the tacky gamer/marketing features of the keyboard (various backlighting modes, like a "snake" that goes back and forth between your keys) it's a fantastic keyboard.
It works great on a Mac, the include a replacement spacebar which is way better looking than the ugly "backlight dragon" that advertise with the keyboard. It came in at just about $140.
Mechanicalkeyboards(.com) usually has the harder to find mechanical keyboards in stock.