It's an activity heart rate monitor...aren't they pretty much a commodity at this point? What does one do that other can't do?
I bought one on Amazon called 'Moofit' for $20 and its worked fine for a year now. I expect it will continue to work fine for another year.
I don't like to buy cheap and replace often, but if the expensive stuff also doesn't last a long time, what's the upside to paying more?