I don't need the $100+ keyboards or anything, what REALLY makes a difference in my playing is how smooth the feet of the mouse are, and how comfortable the mouse is.
I had a $10 cheap ass mouse, was the most comfortable mouse I've ever used, but then the cord wore down and it stopped working, and I lack the skills to fix it. Bought a Microsoft Habu, didn't like it at all. Bought a Logitech G5, love it. Bought a steelseries mousepad, OH MY GORSH. My KDR in games (particularly sniping in TF2, where headshots are near essential) nearly doubled. EVERYTHING is so much smoother when compared to my (what I thought was smooth) desktop. It just glides, no more rugged, scratchy mouse movements, it's amazing.
For keyboards, I have a Razer Arctosa, which I bought because I LOVE the flat keys, and the low profile. No need for fancy backlighting or macro keys, I just want it to be easy to type with and the keys to not be curved.
I'd advise ANY gamer who doesn't already have a mousepad to get one.