I have 1 X pristine Astronomik 11.8nm Halpha, 50mm Square unmounted (circa Nov 2011): $250. This is the anti halo series - see
this image of the HH, the best test of halos in a system
This is well below replacement cost and includes postage in Oz
This is 1/2 the price of a new one, so don't miss out
Mike
