Here's a nice-looking 20" Swish Knocker. Although $99 might not seem like a great deal, consider that it's a late 70's model, which will probably have a nicer, less bright sound than the current Swishes. Also, 20" Swish Knockers seem pretty uncommon; most of the ones I've seen are 22".
That one's tempting me--I'd have pulled the trigger if it weren't for the crack. His pictures don't really show the extent of it...$40 Zildjian 16" China Trash