Does it say how much they want for it?
I think something like 30$ to register the domain, no idea how much the webhost would be.
Knowing WoTC, they'd probably hit you with an infringement lawsuit if you tried.
Ah, but re-read the announcement
We encourage past and current users to retrieve any information you want to retain from the Community Forums for both Dungeons & Dragons and Magic: The Gathering.
there's a pretty decent case to be made that they accidentally issued a free pass for taking the whole forum, just change the formats so it no longer uses their gif/jpgs and you'd be set to host all the user generated threads on a new forum.
Anyway, i'm running one last sweep to try and nab everything i didn't already save. I don't know if i'll make it in time for the whole forums, but i saved the old (ruins of the ) 3.5 forums for nostalgia's sake first so i'm content.