To put things in perspective, just the processors in a cc2.8xl are $3200, a dell with 4GB of ram and something similar to those two well over $5000. You would need one hell of ROI to make that work. Of course lower end/used stuff is cheaper but storing/powering and cooling 50-100 servers aint cheap.
Yeah, but nobody is going to run Intel Xeon processors in a desktop. They're horrendously expensive for their return.
I paid ~$80 for my AMD Phenom II X5 955 and it churns out ~0.80 chains/day.
I paid about $100 per 1.00 chains/day, whereas Amazon paid $1200 per 1.00 chains/day.
You don't need server grade hardware for poor man's number crunching.