Best cable for a long, long run?

I need help choosing cables to make some long runs from our amp to our speakers. We also need long cables from the amp to the preamp. The run from our 'built-in' stereo cabinet to our new speakers is about forty feet. I'd like to make this run under the floor, running the cable through the ceiling of our finished basement. I also want to relocate the amplifier to the basement, just under the cabinet, and make the speaker cable run from there. This means an 8' - 10' run from the Levinson 380S preamp in the cabinet to the Levinson amplifier in the basement and then the 40' run from the amp to the speakers, which are Revel Gems. I'd like to use quality cable to make these runs, but with these lengths it could get pretty expensive! Is there a 'price-range' I should be looking at to insure that I'm buying something suitable? I really don't know much about cables and would appreciate any suggestions or advice you might have on how much I should spend, type of cable, brands, etc. Thanks for the help! Kurt