I posted a build for a clones stand made out of pvc, including lights, vent fan, and casters, seems like around $100.00 us. A propagation box in a Green house has light, some of us call it the sun.
You will not need a filter, and the fans you will want is dependant on how closed an eviroment you use. The fan i used when I had a closed enviroment cost $5.00 us at wally world. The propagation light don't put out a lot of heat, there made to not burn seedlings and clones, that why they call them propagation lights.
Some of the statements you make leave me with more questions than answers, let me explain. A 600 watt light produces about 95,000 lumens of light, so 2 would use 1200watt and produce 190,000 lumens. A single 1000watt would produce 195,000 lumens. Why would you consider 2-600's?
You talk about growing sog to increase yield, but you want to grow bigger plants.....hhmmmmm. I am thinking you don't understand sog or you don't really want to grow sog, which is it?? VV