Suggestions for bang for your buck speaker cables

I don't think my speltz anticables are getting the job done connected to my Definitive Technology speakers. The 14" powered subs of these speakers are not moving as much air as I know they are capable of and the highs are somewhat rolled off. One problem I have is that I don't want to spend thousands on speaker cables for my long runs of 18ft. If I go with the usual cable suspects (Wireworld, Cardas, JPS) in long runs it will cost a lot of money. That's the reason I've gone with less expensive wire like Tara Labs Omni, Analysis Plus OVal 9's, Signalcable and now the anticables. (I may even try Signalcables again). Can any of you recommend a good copper cable that's a bang for your bucker. I've read good things about these lesser expensive brands: MAS, LAT, and Reality Cables; some have said home depot wire. Needing 18ft. runs I'm looking for cables that deliver solid low end, (help fill in a lean speaker) but don't roll off the highs and offer palpable midrange but won't cost near $1k or more. Any suggestions from your experience? Thanks