At the last auction I was at, a Satan's Hollow mini went for $150.  It was kinda dirty, but in pretty good shape overall.  A quick search on RGVAC turned up a $250-$375 range on a Satan's Hollow full size, depending on condition.
But I go more by "what is it worth to me", instead of what a game is worth to other people.  If you really like Satan's Hollow, then go for it.  Although, it is always nice to find out when you got a pretty good deal on a game you like, too!  
