Make your own RCA patch cables.

I've heard of people cutting up a Cat5 patch cord (one with stranded wire) and using that to make a twisted pair RCA cable. All you have to do is solder RCA plugs on each end, and there are 4 pairs so you can use one cable for 4 channels. Cost to make one should be well under $10.

Or you can use RG58 coax (available from Radio Shack if you don't have any thin ethernet coax cables). It's 20 cents a foot and probably much better than what the average RCA patch cable is made with.