you can get a kit for moon lights from e bay for like $20.
and agreed the 2 footer is a little off on the price, that was just a quick pull of items, i paid 110 for my 4 lamp and when i was lookign i remember the 8 lamp version for 130ish i believe.
you'll need more then the 6500k lamps, you could get away with two of them but you'll want some blues and daylights.
that beign said with a 8 lamp system you'll probably be able to only grow SPS
and clams, and an 8 lamp fixture is abotu 24" wide so it won't fit to well
a 6 lamp is all you really need for a 18" deep 125g, then you can have an assortment of corals from the sand bed to the top, SPS
will even fro in the mid sections.