I would suggest that everyone who wants On Lisp but doesn't have it
consider sending a letter to the publisher asking when it will be
reprinted, thus signalizing a demand directly to the publisher. In the
meantime, lots of libraries have it. If the local library doesn't, use
interlibrary loan services. The code from the book is on the web now,
and should continue to be understandable once the book has been read
and returned to the library. If need be, borrow the book from the
library again.
As far as ANSI Common Lisp goes, it's still in print. If the English
version goes out of print, learn German and buy the translation ;-)
George