At what point is filling doubles two fills?

[Chris H]

Many of the people that I know on this board are diving doubles. You come to the LDS of your choice to essentially get your 1/2 full doubles topped off and typically get charged for two air or Nitrox fills.

Throw a $25+ set of fills on a two charter dive and your relaxing morning on the big pond ends up costing $100. At what point should you be charged for 1 fill or 2, and like I've wondered aloud on this board before, WHY CAN'T WE GET FILLS BY THE CUBIC FOOT? I know it is done for the Tri-mix fills. Heck, the PDA program "mixer 1-2-3" even lets you enter the cost per cu.ft in the program and it gives you the $ with the PSI to add to the tanks.

Somebody please step up to the plate so we can use Nitrox all the time and still have money to get on a boat and use it. I know that it will only get more expensive when Helium gets added to the equation, but Nitrox should be cheap!