Love mine
Hi, I just bought one- a Polar A3. It's a mid-end model (under $100). I was also hesitant about buying one because they're pricey and I tried one years ago and it didn't work well. But this is great!
Unfortunately, I just use it for spinning class because during step it irritates me for some reason (I have small wrists and it's kinda bulky). But it's great for spinning because you get to see how hard you're working. Plus, during rests, you can make sure you don't rest too much. It's neat because a lot of times you'll be working way over your target HR and you would've never known it without the monitor (you also go below your target HR too which isn't fun!)
It also tracks your exercise time, avg %HR, time in target HR zone, and it can store the info. So just check out some comparison sites online to find one you want. They're always on ebay.com but you may want the option of returning it.
Good luck!