Whether it is the chicken or the egg, they also
have access to better
 parts stores (for hobbiest quantities) and excellent magazines.  The
 Dutch
 magazine Electuur is translated into English and published in the UK
 every month as Elector.  It has excellent construction articles,
 readily available firmware, and even the PCB layout for most of the
 projects.  
 Elector is indeed recommended.
 AFAIK it also  published the first DIY computer : in May '74 they
 started a series on a 12 or 16 bit TTL-based computer. That is two
 months before the Mark-8.
 Those who like to see something special should check it out : it is a
 two-address machine, no instructions, but memory-mapped "functional
 units". It even had hardware based multiply and divide !