Rex... you didn't put enough ranges in your poll. some of us with bigger tanks have spent a lot more.
I considered making my own at first becuase almost everything I saw didn't look like what I wanted. Then, after reading the horror stories about overdriving lights, I knew I didn't want to go there. I like my house and I like my stuff too much to risk it.
I wanted something that looked really space age, hi tech, and would hang from a vaulted ceiling without looking cheezy like a shop light. So, yeah, I spent a lot.
On my 120 gallon show tank in my living room. I spent around $600 for my Giesemann setup including bulbs and extra hardware (got some nice chrome stuff from a commercial retail store display supply shop).
I was looking at the corallife lights that clamp on the back too. 2 250 Watters... But I'm really happy with the 600 watt light setup I have now. It gives me about 5 watts per gallon. I needed that since I've got a deep 120 show tank instead of a 120 long. I think with the shallower long tank I could have gotten away with less watts per gallon. But I like the look of the deeper tank better (lots of depth when looking at it from the front, so I can have tall and short plants arranged in some cool ways). And I've got the light to reach the bottom of the tank for my short plants.