Looking for a power cable upgrade

I got an itch to upgrade. The sound I'm getting now is great I like it but like most of us I'm want to look at the other side of the mountain for some thing better. This is what I'm using right now:
Im looking at spending around 500.00 per cord either used or new, and also would try a diy solution. If anyone as used my current cables and has moved to something else please comment. Or if you have found something fantastic please comment as well. Any input would be great.