I also tried communicating with several Midwest buyers that I found on a well known forum. When I asked about yields of precious metals and so forth I was met with defensiveness and, in one case, downright hostility. Not good! finally I found the folks at cashforcomputerscrap.com. I was reluctant at first, but their prices were great and I didn't get any of the negative "vibes" that I'd gotten from others so I thought I'd give them a try.
My test shipment was approximately 15 pounds of CPUs and 8 pounds of ram chips. I entered the info into their website and they arranged for and prepaid the shipping - a very nice touch. I got more money than expected and I had a check within a week or so.
With this success I decided to send them the larger load of telcom boards that I mentioned above. This was around 700 pounds of material. I checked around first and got quotes on shipping a pallet of this stuff and found the cost would be anywhere between $600 and $900 and payment had to be made upfront. I checked with cashforcomputerscrap.com and they, as they did before, arranged shipping and prepaid it saving me a lot of upfront cash. turns out the deals they get on shipping was 1/3 of the quotes I got for same from the same company - quite a savings.
Bottom line is that I got nearly $7 a pound for material that others low-balled at 50 cents! I had a check for over $3,000 (material less shipping) within a week or so as before. Such a deal!
I've been in the scrap and recycling business for decades and have run into a lot of scammers and ripoff artists AND a lot of good folks as well. I hope that my experience helps guide you and that my recent "learning curve" will be of benefit to you. Note that this is NOT a paid endorsement. I get nothing out of the recommendation except for the fact of knowing that I've passed on what has worked best for me.
Mike