The cost of components in order to make a frame for a mining farm is no more than 6 dollars for me, and 40 minutes of time if you are not in a hurry. Some miners make the rear wooden rail 40x15 from aluminum. It costs a little more, but I don't see the point. My wooden frame does not heat up.
That isn't separated! I mean, the right and left rigs are assembled, that's why I think $15 is fair while I just sit back and watch my guy work 
Yep, no heat up! No cooling system yet as these are my first-month rigs when moving to GPUs mining!