For anyone that might be interested, Tillman Crane has a few copies of Structure still available. I had been wanting a copy, but thought it was out of print. Checking his site found that he still had a few copies.
note: hope this is OK, if not the mods/Sean can delete
Update: The book arrived today and have to say it is one I would recommend to anyone. If you have the extra funds, it would be a shame to let this get out of print while there are still copies available from Mr. Crane - and it is a very good source of inspiration.