They're < $35 in volume. Given that the Wahoo ANT+ Dongle is $16 in volume from the same OEM (Wahoo has their own firmware), one has to wonder how high the price for the HRM might be.
I fully expect Nike or Adidas to bring these to market, leveraging their very large channel and ability to take down more than the MOQ (5k pcs) to drop the price to around $45 at retail.
http://www.wahoofitness.com/wahoo_blue/