1SaleADay via Sears offers the Bowflex iConnect Fit Wireless Heart Rate Monitor Kit for iPhone, model no. BOWFLEX-FIT-PK, for $9.99 with free shipping. That's $20 under our June mention and the lowest total price we've seen. (It's a current price low by $23.) It displays your heart rate on your phone and tracks the intensity of your workout.

Of note, although the product page claims hardware compatibility with Android devices, there aren't any available compatible Android apps.

Update: Link updated.