I bought 2 PHBs and the 3 core gift set. I've introduced some friends to the game, and bought the extra PHBs so that there would be plenty to go around the table. That said, I expected them to buy one at some point, which two have.
Also picked up KotSF, which was kinda neat for me, as I was feeling lazy and uninformed at the start of 4E. I've bought most of the stuff on the poll, including the very tasty Vault and FRPG (for the crunch only), but skipped the FRCS; I'm an Eberron guy at heart.
Here's hoping that Eberron turns out ok.