You mentioned the US Roaster 3K...what does one of those cost? I have no business plan, no intention to "roast for revenue", but have to admit that I too "have a fondness" of having a roaster like that for home use.
My 3k ran $11,650 (plus ~$450 freight IIRC) back fall '07, before anticipated early '08 price increase. This included IIRC ~$4,500 customizations above base model price with PLC profile controller, end of batch auto-dump, over sized fan to enable simultaneous roasting/cooling and ethernet interface.
I must also mention the USRC roasters are under-rated batch capacity wise, 3k=6.6#. I routinely do 8# production batches no problem. Not some 20+ minute roast time either, even though pushing it's capacity 21% over rating can do still do ~15min City. My darkest roast is my Vienna Gloriette Blend, ~40sec into 2nd, with profile built targeting 16:30 EOR. Just finished a couple 8 pounders of it. First batch finished/auto-dumped 16:37. Oh bummer, missed EOR target by 7 seconds while off working on chain hanging platform for speakers.
THAT is why I spent the extra bucks for the profile control system. Once profile dialed in I can multi-task bagging previous batches or whatever while roasting.
FWIW I'd take a USRC over Diedrich any day. While the Diedrich IR's are supposed to be very energy efficient they don't have the batch capacity of comparable batch sized USRC. So what if I can ONLY get about 40 batches from a 5gal/20# propane tank. That comes out to ~$0.30 per batch/$0.04 per LB greens:o Ok realistically with pre-heat and doing some smaller sized batches lets call it a nickel a pound. Yeah, over a year and a half with the USRC 3k and a few tons roasted and still way pleased with it's performance, including including in the cup of course.
I would not recomend the USRC 3k as a "home" roaster. I have done as small as 1# batches and could do smaller I suppose but use the CCR HotTop for itty-bitty batches. Realistically the USRC 3k can roast ~200LB in an 8 hour non-stop roast day though the most I've done in one session was 160LB. (but not 8 hours roasting either)
Gotta stop playing around typing, still have work to do before going home!
Ultimately the quest for Koffee Nirvana is a solitary path. To know I must first not know. And in knowing know I know not. Each Personal enlightenment found exploring the many divergent foot steps of Those who have gone before.