That's because its not anthracite. The lowest consumer price for anthracite is going to be around $120-$130 per ton if you pick it up at the processing plant yourself. It's only mined and proccessed in a few laces in Northeastern Pennsylvania, it all has to be shipped to Western Pennsylvania which FYI has a very abundant supply of bituminous coal.
This shipping of course is going to add to the cost,off the top of my head $200 plus. Anyone selling you "anthracite" for less than that is giving you line of crap.
Jerry will have so more info for you on using bit coal in your stove but i'm pretty sure he's going to tell you that you can't. Add to that it should be properly sized no matter the type.