agree leh.
must factor cost, manpower, venue, canopy and shelter,
officials, license, security, block the roads (dunno need $ or
not), liaison with bus company (divert buses away),
advertisement/publicity, t-shirts/goodie bags, equipment, lotsa of
ambulances and 1st aiders (1 ambulance +2 first aider is around
$800cheapest), photographers/videographers, press liaisons, and
erh.. many more? 
It must also be taken into consideration that this time round,
there will be three starting points with three totally different
routes - it was in today's papers.
In other words, compared to last year they must block off many
more roads, and the logistics load will be doubled since more first
aid posts, water points, security, marshallers etc will be
needed.
For all that, $45 for the full marathon is a bargain.
