620 is what I keep seeing here. It could go higher. Occasionally I see 580, but the consensus seems to be 620.
I would talk to a local lender. Have them pull your credit report and see what can be done to improve your score. It will take time. It will take commitment. It is possible to do in a few months for many people.
You could also look at http://www.ftc.gov/bcp/menus/consumer/credit/rights.shtm and find the way to get your free once a year credit report instead.
below is a blog that gives some good ways to improve your fico score. I hope it helps.