I just went to Home Depot and found their big wire rack that's full of spools of various types and gauges. Found a 12AWG two-conductor spool and cut to exactly the lengths I needed, plus a little extra length to give myself some flexibility on speaker placement. Dirt cheap and works flawlessly. I don't think I paid more than $5 on the lengths I needed for my fronts.
I'm probably running a bit too thin a gauge (14 gauge) for my surrounds given the distance. I had to feed the cables up through the wall and through a very small opening in a truss brace to route them through the attic and back down the wall behind the couch. But they were the only ones that would fit through that opening. But they don't take the brunt of the signal anyway so I've had no problems with it.