Problem with building your own is that if you don't like the result you're pretty much stuck as you probably can't return them and probably can't sell them for very much if anything. That said, I plan on doing that with some Supra Lorad 2.5 or DH Labs power cables and some decent Wattgate connectors and see what happens. Has to be better than stock cords and I'm only out around $75 or so in the event they don't work out.
Another alternative to buying used is to try some of the direct sellers who generally have good money-back trial periods. Companies like Triode Wire Labs, Grover Huffman, Morrow, and whatever MAC is called these days would be some good ones to try. Their 10AWG cables are a little more than twice what you're looking to spend (you can use a smaller gauge for source so will be less), but you get to try them for very little cash outlay (other than possibly return shipping) and they may very well end up being keepers given the fairly consistently positive feedback from owners here. You could even try several at the same time if there's enough room on the ol' credit card, which would probably be the thing to do given how differently PCs can work in various systems. Just another thing to consider.
By the way, while we're on the subject of power you might also consider upgrading your power conditioner at some point as well. I also have the APC H15 in my home theater system and tried it briefly in my audio system and it's not the most transparent unit out there (compared it to an Audience unit). It'll probably help you reap even more of the benefits of better power cords as well I'd think. Always something. Hope this helps and best of luck.