According to wikipedia
The pulse rate can be used to check overall heart health and fitness level. Generally lower is better ...
Thus I could use my pulse, as a measurement of my fitness.
However, I've heard from two separate sources though, that both; a) The time it takes for the pulse rate to "recover" from vigorous exercise; and b); Looking at patterns of millisecond delays between the heartbeats; gives a better indication of fitness than resting pulse alone.
I'm wondering, what method(s) gives a an accurate measurement of my fitness, without being "expensive".