You can buy Redhat Linux CDROM, Debian Linux CDROM or Slackware
Linux CDROM which already contains the PostgreSQL in
package form (both source code and binaries) from :
Cheap Bytes Inc Web site:
http://www.cheapbytes.com/ (7 U.S. dollars)
Debian Main Web site :
http://www.debian.org/vendors.html
PostgreSQL organisation is also selling 'PostgreSQL CDROM' which
contains the complete source code and binaries for many Unix operating
systems as well as full documentation.
PostgreSQL source code is also available at all the mirror sites of sunsite unc (total of about 1000 sites around the globe). It is inside the Red Hat Linux distribution in /pub/contrib/i386/postgresql.rpm file.
For list of mirror sites go to
ftp://sunsite.unc.edu