Seeing GWX is "freeware" and made with other mods that are free, plus what the GWX Team has done, the only way it could ever be sold is if all that are a part of it got a piece of the "action". And I doubt that will or should ever happen for the obvious reasons.
But if it was possible, I agree with Pants. Use the proceeds for a good cause. Like helping Neal with SS and Terrapin with his site, if he kept it going. I believe that would keep everyone involved happy. Even if it's put on a CD or DVD to pass around for those unable to download it, use the money to pay for the discs and what's left over go to the sites mentioned. Afterall, without the SS and UBRS sites we wouldn't have a place to bitch and moan and get these free downloads.
Just my inconsequential 2cents.