3 gun shows ago, there was a guy selling 1000 cases for $150.

For real?

For processed brass? I see people wanting $100+/1000 for mixed headstamp range pickup.

Well, 3 gun shows ago puts it back in April 2013 when things were stupid crazy.  Not sure how much of it he sold.  He had 60K cases at the show.

Going by the OP for "processed" I can honestly say that I haven't seen anyone selling any other than just cleaned as everything else is so time consuming that I can see that it just isn't worth it $$-wise over just selling (or in your case) buying new brass.  IMO that's asking a lot from a once fired brass reseller to resize, trim, swage & clean.  I only do a single loading block in a session just because it takes so long to do all the steps to properly process brass.

Seems to be some confusion, let me explain:

Between my work schedule and the price of primers, I don't shoot as much as I'd like.  In turn, my expensive equipment sits idle.  I've made a deal with a guy that scraps a LE range's brass for all his rifle brass.  This works out to 5-10k of 5.56/223 every month.  I'm finishing up a 50lb capacity wet tumbler to clean all that brass better than new.  It isn't any more trouble for me to size and trim as there are no extra steps and everything is paid for already.  The only concern I have is wear on my case trimmer head. Basically, I load clean cases on one side and finished cases poop out the other.
Once I get my annealing machine setup I'll be able to offer that as well, in addition to 300 Blackout brass (although that does involve an extra step).

So what I'm trying to get is a fair market price, which seems to vary without much rhyme or reason.

Case trimmer cutter wear is unavoidable but the carbide cutters seem to get a bit more mileage than the regular hardened steel ones.  Lubing/sizing & trimming is pretty time consuming but your trimmer setup sounds like it can handle high volume with little trouble.  I'm working with a Hornady hand crank cutter with a motorized deburring & primer pocket machine thing and when I'm in a rhythm I can trim/deburr/lube/size a case every 30 seconds and after that the whole block goes in the tumbler...which isn't quick but also isn't that slow either.  Now if I'm getting what you are asking, you are looking to sell completely processed brass and you want to know a fair price to sell it for??  If so, I would say 20-25% cheaper than new brass IMO.   

My Dillion trimmer makes it a no-brainer. Once in a great while it will spin a case, but it is just about instant.