[Nebthet]

A Sunlight Supply Tek 6x54w fixture will do you perfectly for your size of tank. I would say an 8 bulb fixture is better suited for tank 24 inches wide.

I have a 36x18x22 high and use the 6x39w fixture and I have to keep chalices, acans and xenia on the sandbed because it is too bright for them higher in my tank, so the two inches extra on your tank will hardly be any difference, especially if you use ATI bulbs.
Aquablue special and Blue plus seem to have the most par in them.

Giessman bulbs are also really decent and I use Blue plus and Actinic plus on my tank.

The difference in the bulbs between the cheap and expensive can be drastic.
The cheaper bulbs have less usable par and they have a tendency to loose than earlier than the better branded bulbs.
ATI is one of the top brands for bulbs with Geissman being right behind them in terms of the par values.
The new KZ bulbs are getting great reviews and have par values to match either of the previous two.

Search for pricing on your bulbs. If you cannot get them locally, order them in. I have seen ATI's sell for between $23 to $33 for the 36 and 48 inch bulbs. Keep an eye on sales also, and buy your years worth of changes then.

I know Oceanic Corals sells ATI bulbs and JL Aquatics sells KZ and Geissman.