Affordable Power Cords

The original Absolute PC was very nice tonally IME. It did little to nothing at lowering the the noise floor. There is now a Mk. II version that I haven't tried.

There have been several threads about this topic, there are numerous suggestions. Others may disagree, but my experience has shown that quality connectors are really important, at least as important as the wire. This means that you aren't going to get much for $50-100 (retail for a preassembled cord) that is going to sound like a real upgrade. If you are willing to spend a bit more and spend a little time on a DIY cable, you can get a REAL bang for your buck. Cryo-Parts ACIII cable, Parts Connexion's DH Labs cable, and the Tunami are all good bulk DIY ac cables that you can turn into fine cords with Marinco or Furutech connectors. DIYCable.com has lots of parts and instructions. If you have no interest in DIY, occasionally some DIY cables are sold here made from good wire and parts and are a good value (as long as they are correctly assembled!) Another good value are Shunyata cords that have the inection molded plugs (Diamondback and Venom.) Galen Carol Audio sells the Venom for $89.00. That's the one I'd be most willing to try (preassembled) at your price point.

Another way to make even modest up-graded cables sound better is by adding a good receptacle, such as
http://cls.audiogon.com/cgi-bin/cls.pl?powrcond&1195691123 the ones Albert sells here on A'gon. They will make a difference, and providing you can install them yourself, there will be minimal impact to most budgets.
I also agree with other posters on Signal Cable. My findings were similar. For better refinement, especially on a budget power cable, you might want to try this company http://www.ultimatecables.com/zencart/index.php?main_page=product_info&cPath=66_67_68&products_id=186
They are a silver/copper hybrid, cryo-treated cable and are priced nicely. I believe $85(CDN) for five feet.
Decent pc at real earth prices can be found.

Consider the DIY route. See Parts Express for an easy to follow procedure (plus the necessary parts).

The most affordable is the one the factory provides.