I bought some .047 piano wire in bulk here: http://www.fastenal.com/web/products/_/Navigation?term=&termca=&termpx=&sortby=webrank&sortdir=descending&searchmode=productSearch&zipcode=&filterByStore=&filterByVendingMachine=&r=~|categoryl1:"600930 Raw Materials"|~ ~|categoryl2:"611723 Wire Products"|~ ~|attrdiameter:603260|~
It's 170 Ft of wire and cost me four bucks and some change because we (my employer) deals with this company all the time. Yes, it comes in a coil and requires some straightening to install, but for the price I couldn't beat it. I made Z bends on the control horn end with needle nose pliers and used the recomended linkage stops on the servo ends. So far so good. For longer runs, I would think some guides could be fabed up easily enough to keep it from flexing too much.