I've noticed that Daddy's Junky Music has a couple used cases. At least one was a Guild. Guitar Center in Boston had one, but that was a while ago. Craigslist has them pop up from time to time. I've never seen them cost more than $50 as a point of reference. Just a matter of checking the fit.
i got a very good fitting case by going in my local guitar store with the guitar. I think it's designed around some Gibson or other but it was cheap and good.