Be open to negotiation. Those stuck at the point where double the CPM's were the norm are running on empty today. Many publishers grudgingly do this and some refuse to do it. Deliver what you offer or promise. The majority of the email list ad networks require placement in the top or best position.
Many publishers still try to give a middle or lower position ad for a top position price.
This is a surefire way to get your list pushed to the bottom of the buyer's list. Never underestimate an ad network's ability to send funds your way. Your job is to figure out how you can get the largest chunk of that pie. Ad networks have biases towards large lists that perform. Don't despair if you only have a few thousand members on your list.