How about make the actual contest a %-off code?
As in, go collab with Amazon or (more probably) Newegg to get the system you guys make pre-built, then send the lucky winner a 95% off code.
As MikeyA15A4 said, I'm sure anyone would pay $500 or even $1000 to get a $10000 rig.
is anybody considering the amount of power this rig would use. but i still want one.