Okay, I have experimented a lot in this domain and what I realized is when your budget is too low for a power cord it is best bang for buck to buy a decent copper electrical wire or some neotech wire off the loom and terminate it with high quality plugs from Oyaide. At the lower end conductor material and geometry is pretty much generic and it is the connector which takes the performance to the next level. I have done this extensively.
If you have to buy off the shelf, talk to Chris Ven Haus and get one of his "Flavor" cords based on where you want to put it.
In both these cases if you dont hear much differences you are better off upgrading your source. I would anyday go with first method of highest quality connectors and any decent copper electrical wire.