*fuzzy memory alert* I think Andy L. mentioned on the google theater sound group that they'd made a short run (50 pieces?) and decided to make a couple of changes. The original run was for sale and, IIRC, and they were taking orders for the revised units. You might try contacting Andy directly.
+1 to Riley,
I think I've emailed/called a couple times in the past with no result.
I tried some searches on the theater sound list and didn't see anything recent like Tim has described. oesn't mean it's not there however.
Does any one have a link to Black Dog Audio? Their name is pretty much un-googlable (as is Duck's Echo Sound).
Thanks
Philip