How can I know how much a property will actually rent for?

[Jack Galloway]

There are lots of good deals in my area and it is a strong renter market. The variable that I don't know how nail down is how much a property will ACTUALLY rent for per month. Agents and prop mgrs seem to want to guess high. But I need to have a more realistic opinion of what houses in one neighborhood rent for vs a similar neighborhood across town. Any suggestions? Jack in Franklin TN