Here's the specific drawing in the Switch FAQ that describes what Lak7 said. That'll get you eight LNBs without much fuss, money, or bother. Any receiver should be able to control the simple switch array, too.
Do you have specific needs beyond eight LNBs and one receiver? For 8 LNBs and 4 receivers, this post is the most simple switch hookup. Again, any modern DVB/FTA receiver should be able to handle the task.