Provided they pay in advance -- they're notoriously difficult to get any money out of after-the-fact. My personal opinion is I don't mind if Sage attends though I think they should be paid and in advance. The $2,000 level sounds about right and we should have a clear idea of what type of involvement they want (how much time).
Putting them toward the end of the day (3pm ish?) seems like it would help keep the time from going way overboard.
Since most of the policy is set already - I'd want to be sure we did not mislead the group to think that the sessions would be changing much at Sage (probably most people already know that).
TL;DR: Yes to $2,000; don't care who from Sage attends or for how long provided they don't get a slot that goes all day (put them at the end)