I'm finding that you can get a very simple heart rate monitor that stores and recalls statistics for your pulse from $50-$70 with all kinds of nice data dumping stuff ... or go up to $300, $400... and still have a heart rate monitor that can dump data to your computer. Under $150 it's hit-or-miss, they may have funny features like alarms above/below a certain heart rate, or the ability to recall statistics, but no way to download them; but once in a while you find one around 50 bucks that does data dumping.
For five hundred dollars, you still cannot find a heart rate monitor with a freaking temperature probe in it.
I mean, some of these things strap to your chest, and yet ... they don't attach a probe to your skin.
I guess monitoring body temperature is hard. It couldn't be as simple as dangling a thing similar to a bluetooth headset on the ear as a probe.