http://www.amazenproducts.com/ has some great pellets that do not use fillers
www.cookinpellets.com also has some great pellets that do not use fillers.
Both have multiple types, to include a great blended option such as "Pitmasters Choice" or "Perfect Mix" that works well for most cooking needs on a pellet smoker. These are blends of Cherry, Hickory, Maple and or Hickory, Cherry, Hard Maple & Apple, neither have alder or oak fillers.
Many brands such as BBQ Delight and others do a 60/40 split. where as its only approximately 40% of the flavored wood (apple, cherry, hickory, etc), then the rest is Oak.
For pellet smokers, most here include the use of A-MAZE-N-TUBE-SMOKER(
AMNTS) or A-MAZE-N-PELLET-SMOKER(
AMNPS) to produce the smoke wanted for flavor. Pellet smokers often put out little smoke, especially when cooking at heats above 225 or so.
Even those thast use MES will put in use the A-MAZE-N-PELLET-SMOKER(
AMNPS) to get the smoke they want.
Good luck with your hunt.