Amazon's price for the P1 [amazon.com]
is $150 and they've never been cheaper than $148 according to the tri-camel. These have a built-in mike and remote and are obviously designed for smartphone use - no amp necessary. If you've finally realized the earbuds that came with your phone sound like crap, this is your answer.
According to Massdrop, the PX was created from the P1, with an updated build quality and lower price. Unlike most Massdrop "drops", this will ship within 3 days.