Of all the cheap power cords, the Absolute Power Cord ($49.95) is the only that's a *tuned* design. When cryo'ed, it is really really good and will defeat $500-600 power cords. If you want to go the DIY route, Chris Ven Haus came up with a new, custom cable design. I've seen it, as Lak bought a kit and it looks really good. I'm looking forward to listening to it. He says it sounds really good...
DIY and untuned designs need the use of an external tuning device. I use the Highwire Wirewrap ($25) and it works really well.