That's very true, in fact my current mining rig I build myself. Problem is, it literally took a month. At first I ordered a 6970 and powersupply but the GPU wouldn't fit on my motherboard. Then I bought a new motherboard, RAM and CPU, but the motherboard was an ATX and my case was an ATX-mini. Then I bought a full tower on craigslist and it wouldn't start up properly so I had to return the motherboard and GPU. Now it works and I'm going to add another GPU on the second PCIe slot if I win that bid on ebay. I still want to get another mining rig though since my electricity is free. I figure it's comparative advantage. I just want to do it properly and have it cooled and OCed properly so as to be sustainable. I think I have room for one or two more rigs.

Another thing is, I see on youtube that alot of miners have no case and just mount the board on piece of wood and have a big external fan blowing on it. This seems logical since the fan can be replaced cheaply, you save on the cost of a case, and it's better for cooling, but I don't know how to build that setup. Do they drill the holes for the Mobo themselves or do they buy it somewhere? I work a full time job so I'd rather have an expert do it correctly for me. "Reasonable" for me would be the cost of materials plus a few hundred. I figured that at this bitcoin prices, a few people will be willing to sell some rigs.