I'm in total agreement - its about when to apply effort to fight. And exactly because the disty/mfg don't want us to know, is precisely why this info has value!
I would definitely put this info in - anonymously (CYA on confidential info) - in a strong community share (give a little, get a little kind of attitude). Now, I don't always know the price, especially if assembly is at a CM. But I usually know critical components.
Maybe don't try to aggregate at it first, but just show them as case studies. Customer X got qty Y for $Z in 20yy. Customer A got qty B for $C.
Story time: one of my sales reps once did something they were not supposed to, and opened up Salesforce on their laptop while visiting me. We pulled some parts, saw general sales figures (globally), the manufacturer's "don't sell it for less than..." minimum threshold, and one huge volume customer that was getting a great deal. It was obvious where the final range was going to be after haggling. Since I already new the final price, at that point it was application of enough pressure to get there.
There is a flip side to this as well, which is instead of informing the users of other MFG prices, to alert the MFGs of the parts their users are browsing. So if I spend an afternoon browsing Fairchild parts, maybe parts.io tips off the folks at ST and Infineon as to what I'm up to, and I get an unsolicited call or email. It achieves the same goal via different politics.