You are way off on power supply cost. I'm driving my 30 Cree LEDs with a CC source I made with an old computer power supply for about $15.
My blue Cree LEDs were $4.85/per.
My white Cree LEDs were $8.25/per. I use this outdated model of LED by Cree. But I got a deal buying in quanity.
http://www.kaidomain.com/WEBUI/Produ...px?TranID=2663
I also use an optic just like this, except I got mine a little cheaper than $1 each.
http://www.kaidomain.com/WEBUI/Produ...px?TranID=1603
My 30 Cree LED project has been working for months now, and will continue to work for years with no maintence. I've got about $200 bucks into it. My tank has way too much bottom area (21 square feet) for it to provide enough light to do much on it's own, It's mostly blue and I use it as extra suppliment during day/night transitions. The project purpose was mainly just to see how I liked dealing with LEDs on my tank. Compaired with the 12HO T5 bulbs and the 4x MH also in the lighting setup, it's barely noticeable. However, its also barely noticeable if the 4x MH bulbs are on once the 12x T5 bulbs are lit. I have to bend down and peek.
Yes it can be done for relatively cheap. I did it, and I like it. If he were to experiment with driving LEDs and heat sinking and CC supplies, he could do it as well. Likely for under $600.