I have been doing a lot of early morning cardio (jogging/walking throughout my neighborhood) and would like to purchase a HR monitor to keep me in check. What do you guys suggest for a cheap and effective HR monitor? I was looking at a few on ebay and I think I am leaning toward one of the watches that does not use a chest strap, are these decent? I think I have read before that the brand Polar was pretty good. Thanks for your insight!