Harbor Freight sells 3' flex drills for pretty cheap,
Parts Express sells 16' USB cable + repeater for pretty cheap (and you can chain up to 5 of them)
and HDMI cables go up to 50' (VGA is cheaper, if that's an option for you)
This is what I did to connect the projector in my livingroom to my computer in my office. But actually after doing that a while I got tired of always needing my personal PC to be ready for use as an entertainment center, and just got a second computer for the livingroom and put Windows on it so my friends could figure it out. That way I also don't care if it gets full of malware as people download things; I just wipe it if anything doesn't look right.