Reasonably priced, well matched speaker cables

I'm looking for some recommendations for speaker cables to use with 4 B&W Natutilus 805s + 1 HTM2. Because I'm going to need a 40ft and 30ft length run for my rears speakers, price is a concern, but I don't want to I'm willing to use different cables for my L+R main channels however which will be 12 ft; is this a bad idea? Should the center match the L+R main?

The speakers are all driven by a Rotel 1075 multi-channel amp. 25% multi-channel music, 25% movies, 50% 2 channel audio.

Anyone have an opinion on Silver Sonic T14 line?

Thanks.
-j