To be honest, whether you start with two or three sows, you will inevitably end up with the same problem of having to add another piggy for company. With sows, you have the possibility to look for younger sows or a neutered boar. A trio of sows can work or not, depending on the individual balance of personalities. I have and have had successful trios and others that didn't work out.
There are some rescues in the USA, comparatively not as many as in Britain; shelters can also have guinea pigs looking for new homes. You can find a local ones via petfinder. Generally, you will find that piggies are preferably being rehomed as same gender pairs.