I honestly do not know that you will find an "expert" about adult mailing, and their value. There are sooooo many variables that go into mailing, and the value of it, that I simply think you're going to be getting shots in the dark. Even on the mainstream side of things, they can only give you a "guesstimate".
There are really just too many variables for a black and white answer in a court of law. I would advise you get get some mailers from a mainstream mailer business forum, and have them talk about the value of a mailing list, and how it's handled over time, etc.. Use them as your "experts" to give some idea on how those things are assessed a value in that regard.
Good luck chief.
