Original poster: Ed Phillips <evp@xxxxxxxxxxx>
Lindsay books carries it: http://www.lindsaybks.com/bks/expphy/ Worth every penny of the $26.
Lots of detail on making ionization chambers, GM tubes, etc.
the other good book ( a bit priceier at $60, but much more modern) is Building Scientific Apparatus, by Moore, Davis, Coplan, and Greer
http://search.barnesandnoble.com/booksearch/isbnInquiry.asp?userid=ru64ICTCqI&isbn=0813340063&TXT=Y&itm=47
No how to build a GM tube here, but lots of other useful info.
Ed