I have to ask, how many pounds of pellets are consumed in a night long pork butt smoke etc on average?
http://memphisgrills.com/sites/default/files/Pellet Consumption Chart.jpg
This is concurrent with my experiences thus far. Memphis' utilize double wall pits so they are quite miserly on pellet consumption.
Honestly, great deals can be had on pellets so I wouldn't worry too much.