Looking for a good calorie monitor

mary70

I do a boot camp 3 x per week and have used the "Mio" watch type cal monitor. It seemed to work ok at first, but then I noticed it would stop tracking for a while (I'd look down, see the cals and 10 min later in my workout it would read the exact # again). Most people in my class are seeing between 900-1100 cals burned.

Any suggestions for a really good one ? Preferably not crazy expensive.