gamerprinter
Mapper/Publisher
I suspect the Beginner Box may have had something to do with it. People can now start playing Pathfinder after only a single purchase, and that's a big draw. I think Paizo said at one point that it was their biggest selling item.
I'm pretty sure the Core Rule Book is their biggest selling item - 4 print runs so far I think. I'm not saying the Beginner Box did not do well, in fact, it did and is still selling well, but no where near the number of CRB's sold.