Normally pellets themselves are pretty cheap but the shipping costs you. So if they are getting pallet loads of them, the price should be decent. I have never used that kind but I would buy a bag to try if I were you. Normally there is oak in the wood too, and they don't have to label it as a "filler". It is rare to find a 100% flavorwood pellet unless you go specifically looking for them. Most are a 60/40 or 70/30 blend of oak or ash and the flavorwood. Don't be fooled by 100% hardwood either, that pretty much just means they are made of wood which you already knew. I haven't seen food grade pellets with any type of filler thus making them all 100% hardwood.
I like the 70/30 with oak myself. Oak is a good flavor itself. I prefer BBQer's Delight Apple or Hickory for my pellet needs.
XL Big Green Egg, various Weber kettles, WSM 22.5", UDS, Traeger Texas