Almost 100% an add on item to the job, no stand alone sales.
$125 per fixture
$1 per foot of cable
$1 per watt of transformer (600 watt = $600)
Found a few online suppliers I am happy with.
http://www.ccl-light.com
http://secure.fdlight.com/contact.asp
Many more choices, I use a lot of solid brass and copper. Register for contractor pricing. The $10 hooded uplight can't be beat...same as the vista brand.