I do not know what you are currently using but here are some points of consideration. At your price range you can check some cables from Acoustic Revive (triple c reference or absolute) Furutech (nano flux pcocc), Acrolinc (mexcel ducc), even though some of them are near or out of your budget. That's where i would look, for the best copper around. Since this territory is costly i would suggest to try before you buy and probably check the possibility of using the entire cabling from one manufacturer, it will be less costly in the long run.