To build 10 dual processor systems, you would need access to 10 dual socket motherboards, and the chips would have to be dual processor capable, afaik _some_ 486/50's were dual and even quad capable - but i'm not sure exactly which ones, and you would probably have a hell of a job getting the motherboards.
I seem to remember 2 russian brothers strung a load of intel chips together using parallel passing architecture to calculate pi to so many numbers, i think they spent about $70,000 to get 2 gigaflops, maybe you could try something like that ;-)