Make your own speaker cables from 12 gauge Duelund Tinned - copper in cotton, oil impregnated wire. Will cost less than $500 and most likely will sound better than whatever you can buy new or used in that price range (after break-in).
If you must buy a speaker cable built by a professional manufacturer, look into Cerious Technologies Graphene speaker cables.
If you must buy a speaker cable built by a professional manufacturer, look into Cerious Technologies Graphene speaker cables.