AllNeon, while your intentions are good you are completely missing the big picture. It doesn't matter if the seller is good or bad. In the end there is a supplier. Probably someplace like this
http://cavyspirit.com/hollister.htm.
For every pig you buy more are bred to fill the demand.
While the breeders breed, the sellers sell and the buyers buy (creating more demand to continue the cycle) thousands of GPs and thousands more of other animals, are euthanized for want of a home.
Until the shelter's and rescues intake/adoption rates even out (at present for every 5-10 animals dumped in a shelter/rescue only 1 gets adopted out) there is a strong reason not to breed more or support those that do breed. Stop the killing, stop the suffering and stop the abuse. Please don't feed it and please respect this forum as a rescue oriented forum and don't encourage petstore buying.
I posted this link before but I'll post it again in case you didn't read it
What is Rescuing and Adopting?