Here are some listed on petfinder.org
Walden, NY: Adoptable Pets: Petfinder You could also try craigslist. They often have pigs listed and recently there have been a bunch in the tristate area. There are some animal rescues in the area as well. I'm in CT so the only dedicated guinea pig rescue I know of offhand is Critter Connection in Durham, CT. But there very well could be one (or more?) in NY, NJ, or PA.