I took an old 18" single LNB pizza pan (freebie), pulled the back off the LNB, removed all the internal electronics, cut down the feed horn and mounted a copper bi-quad at the approximate focal point. My neighbor and I then shared cable broadband for over a year until I moved last month. I actually built up to setups but only needed to mount one on my house, it worked great across 500', a concrete block wall, their exterior wall and the cheapie (US$15) 802.1g AP sitting in their spare bedroom.
I would never waste a Primestar dish for thie purpose, to many freebie pizza pans around.