First up is the nice website Sw-Box.com. They don't just only hold modified parts for the iPhone but also have things for the Xbox 360 and PS3, just to name a few. My main focus from here is the colored screens and back plates you can order from sw-box.com. you no longer have to have the boring black or just released white editions of the iPhone, you can get just about any color they have to offer!
Second in line is the http://www.focusupply.com they offer stunning color choices. Their colors look amazing compared to sw-box.com, but sw has been doing it little bit longer so i give them more credit. Anyways a huge plus to focus, you buy in bundles. Meaning you can buy the front back and home button all in one click. Simple and damn good looking