Lots of wire and cable suppliers on eBay. I make speaker cables from PTFE (Teflon)-insulated, silver-covered copper. You can buy two big rolls, red and black. Then you twist them - which is actually quite important for noise cancellation, search it - and put some kind of jacket over it (or just tape it). I have a big roll of this stuff called "fray-resistant wire sleeving" that's cheap and looks high end when you slide it over the twisted cables. Then four gold-plated banana plugs and splotches of solder later, you have some really good speaker cables that are an audible upgrade over standard cables. I have some high-end cables from two different manufacturers (one set of which I am embarrassed to tell you how much I paid for them) and this setup compares favourably.
Name brand cables aren't quite a scam, since they are selling excellent cables. But the prices? Ahem. Different cables DO sound subtly different. I sat with my disbelieving wife and we listened to a snippet of a song three times, once each with copper, silver, and silver-coated copper. It was undeniable that each cable sounded a little different. The copper cable was bassier, and the silver cable seemed more pristine. The coated cable was similar to the silver but a little more balanced, and I preferred it - and it was all preference - none of the cables sounded "better." At first I liked the copper due to increased bass (I had been using silver on those speakers). But then, after I heard the other two and came back, I felt like there was a slight thump that shouldn't be there. But we're talking tiny, tiny differences.
Bottom line: cable sound different because of material composition and quality, not brand name, and there aren't that many materials available. If you are building the cables anyway - which is the only way to do it IMO - integrating a brand name wire as a sub component is probably throwing money away. Best of luck!