Actually, "government and educational institutions" can get it free, according to the web site. Probably most readers of TDWG and Taxacom would qualify. Stan Blum writes:

Date: Thu, 26 Apr 2001 12:33:00 -0700 From: Stan Blum <sblum@calacademy.org> To: TDWG-SDD@usobi.org Subject: Re: DIG35 Digital Image Metadata Standard

... Unfortunately, the DIG35 group now charges $35(USD) for the PDF of version 1.0. The draft of v. 1.1, however, is FREE. (So get it now if you're interested.)

-Stan