So if you're planning to set up a patent committee at your company, and you want to bring in external members, is there a standard (or average) payment that one would expect to get? These people would not be patent experts, just like business people, scientists etc
I don't get this at all. Why external people (i.e., people not under employment contract with the company)? You'd need some fairly broad coverage agreements with these people. Non-disclosure, obviously.
And as soon as they see your invention disclosures, the scientists will start iterating on the themes disclosed, so you'd better also tie them up with pre-assignment agreements if they come up with inventions based on reviewing your inventions. That will be problematic, though, because the only scientists useful to you in this regard are those who have expertise in your field.... ...which means they have expertise (including likely many of their own pre-existing ideas), so how do you sort out those pre-existing ideas from things that are instigated by review of your invention disclosures?
Whole thing seems like an idea to be approached with caution and a lot of forethought.
But to answer your question - pay them an hourly rate consistent with their field. Otherwise, you might find the assignment contract mentioned above to fail (as a legal instrument) when needed.