you also got to look at the features - whats available and what you would need
- would you want to download stuff onto your comp to play with pretty graphs
- are you looking at multi sport kinda features ?
- do you need your hrm to lock-in with your watch ? (if you are running with a group of guys all of whom have HRMs this would matter, else not)
- et cetc
the cheaper HRMs dont have most of these features - and do one thing pretty well (that is measuring your heart rate).
The advanced ones (like the Garmin 305/405 etc) - you can have a virtual partner on ur watch whom you can program to compete with you.
compare the features on the polar vs the Geonaute - Im sure you will figure out which model you want pretty fast.