Not sure what type of aerial work you're looking at or the a/c type involved, but I fly for an aerial survey outfit in a C150 and get paid £20 per tacho hour. All VFR stuff, and the bonus is I have a photographer who does all the boring stuff while I get to chuck the a/c around the sky!
Probably a fair level to start negotiations from depending on the level of complexity of your operation and a/c. Enjoy.