Did you just type in NJ under state and choose small and furry for animal and guinea for breed? Marci's rescue has over 130 guinea pigs. Did you look at all of them?
http://www.petfinder.com/shelters/NJ250.html www.cavyrescue.com www.petfinder.com (classifieds ad at the top)
www.craigslist.org www.gpan.net (adoption listings)
Yikes, I see about 30 guinea pigs under classifieds at petfinder. One person has 20 baby guinea pigs (!) and another ad sounds like their poor piggy has mites. Says the pig scratches all the time and bleeds.