Mechanical keyboards are nice if you play more than just WoW :P
The Razer Blackwidow ultimate is a very nice keyboard to get started with, if you are spr serious later on, you can move on to more 'bettererer' (expensive, specialized) mechanical keyboard.

Mice on the other hand are a personal thing. Do you move the mouse with your fingers? your palm? do you have big hands? is it just going to be for WoW? etc etc.