Miles,

you wrote..

The other side of the coin:

If the dollar amount were released with each signing, what would be to prevent an infringer demanding a similar fee? They only paid $x million, why can't we? Plus, as has been noted, non-disclosure of licensing fees can be part of the licensing terms.

I would add..

nondisclosure of licensing fees should definitely be part of the licensing terms..protects both the licensor and the licensee..