Using Craigslist

Even before I became a "rescue," I responded to quite a few ads on Craigslist in which people needed to find new homes for their pets for whatever reason. If you are interested in adopting any animal, Craigslist can be a good place to look, but use caution when reading the ads. If any ads say that babies are being "sold," or are simply listed as "baby guinea pigs X amount each," most likely the person is a breeder (or didn't bother to check the sexes of a pair they bought and want to make money off the accidental litter). More often than not, these people are looking to grab some cash without knowing or caring where the guinea pig ends up.
However, if the advertiser sincerely wants to rehome their guinea pig, they will include an adoption fee and at least offer the cage and accessories as well. People choose to give up guinea pigs for many reasons, including allergies, biting issues, lack of time, lack of money, kids lost interest, moving, etc. This was how I got started...I took guinea pigs that needed new homes because I didn't want them to end up in shelters or as reptile food. It's sad to see so many pets that people simply give up on, and it gets very frustrating. I don't understand how I have 27 guinea pigs and I find time for ALL of them, and yet some folks can't devote even a few minutes a day to just ONE.
Anyway, Craigslist is a good starting point if you are looking for any type of animal. If you do end up going to get a guinea pig and the conditions they are living in are not good, you can contact your local humane society. Most people want to "help" by going ahead and purchasing animals living in filthy conditions, but this only continues the cycle of abuse, neglect and profit at the expense of the animals. Ask a LOT of questions, and don't be afraid to say no if you don't get the answers you're looking for. And don't forget about personal safety...whenever possible, meet people in a public location, or at least take someone with you if you can't.