Toasterhead,
I would try calling SEVERAL real estate brokers in the area and asking their opinions. Try to focus on brokerages which also offer property management services--these guys typically have a decent grip on market rents.
Talking to multiple "experts" helps paint a better overall picture of your market--I've found that some are too conservative and others too aggressive, so relying on any one broker might prove misinformative and, in the long run, costly.
Hope this helps,
RFG