Tomorrow a group of angry New York Mercantile Exchange seatholders will meet with the energy futures exchange’s brass to demand they get CME Group, which is vying to get its hand on NYMEX in a $9 billion deal,  to pay more for the seats they own. Or else, they say, they will scuttle the deal.

They claim the exchange has undersold itself,  for the execs’ own benefit (the execs are expected to fetch a golden parachute worth $79 million) and that their seats are worth far more than the $612,000 they are being offered.

Among the unhappy NYMEX seatholders are a group of members who also own American Stock Exchange seats and tried to extract more concessions from the New York Stock Exchange’s parent company on the same grounds back in January when the NYSE agreed to buy Amex.

But earlier this week, members of the American Stock Exchange overwhelmingly approved its purchase by NYSE Euronext in a deal that will merge the former arch rivals as early as August, if the SEC gives its blessing.

NYSE Euronext paid $260 million of its own stock and Amex members will receive extra shares based on whatever Amex’s Lower Manhattan headquarters can fetch on the cool commercial real estate market. Those terms are the same as what it had originally offered Amex members in January .

But in this case, analysts predict the CME won’t get off as easily as the NYSE did and will have to cough up more money for NYMEX. The main difference is that Amex is seen as a declining exchange while NYMEX trades in the lucrative oil futures exchange business and will fit nicely into CME’s business.