Trapper,
i have a Blacks Creek model 1500. i get a cord an hour out of it with nice wood. i get 8' logs from the loggers.
this machine runs 13hp. A 3.5" cylinder. I had my cylinder rebuilt to a 2.5" rod for faster return times. The bar (18") is belt driven.
Jmur hit the nail on the head with his advice.
The processor is only part of the whole operation, think about your typical log sizes, how to load the machine and how to get rid of the split wood. that's where a lot of time and handling is spent.
I have a hard time believing one could build a machine for much less than a good used one. unless you have a good selection scrap and scavengable parts and really enjoy grinding and welding, and cutting and regrinding and welding, and grinding and welding.....
keep us posted on your progress!