When you say, "adopt one for a friend", do you mean you have a friend and you want to adopt a guinea pig for him/her or as a friend for your current guinea pig?
I suspect that you mean as a friend for your pig. If you have the means and the room (it would mean a bigger cage), I would definitely go for it. It would require a quarantine period of 21 days and an introduction on neutral territory as well.
I see there are shelters and rescues in Murfreesboro, Knoxville and Huntsville. There are two in Knoxville, one is a guinea pig specific rescue.
I don't know if any of those are near you. The rescue I've adopted from is 2 1/2 hours away. Yes, it's a bit far but it's worth it to give a home to a pig in need and I would drive even farther, if need be.
You can also check out your local Craigslist. You might also call your local animals shelters and get your name on a waiting list in case any guinea pigs come in.
