rent estimators/comps resources

[Ryan V.]

What does everyone use to lookup approximate rents in a certain area? I have my realtor sending me properties but they don't include comparable rental rates up front. I'd like to run some numbers before asking her for more information on a property and was curious as to what resources are available and are accurate? 

I'm aware I can use craigslist and search but certain areas don't have enough comps for me to get a good idea of the rents. I've tried www.rentometer.com but I'm not sure how much I can trust it.

Thanks!