Last year someone did some investigating and found that if EACH PERSON got their own dedicated cable connection for their Slingbox, it was the opionion of Attorney X that they would not be violating any copyrights. That's highly debatable (think blackout rules) and there are a number of content providers that would strongly disagree with you (again think blackout rules). There's no case-law to prove it one way or another, but lets just assume it's accurate...
NOW the same person is trying to organize a bulk-purchase of Slingboxes, WITHOUT having a dedicated cable connection for each Slingbox. That's what you're trying to do, isn't it? having Aunt mabel in Sandy hook your SlingBox up to her TV so you can watch games on the mtn simply isn't legal. And it CLEARLY isn't legal. There is no grey on this one. You may as well be organizing the copying of CDs and DVDs for each other...