SFH and duplex, what annual cash flow to aim for?

[Johnny Weekend]

I have been looking at single family homes and duplexes in the 100-150k price range. What annual cash flow (after all expenses and mortgage) do people aim for? Based on my estimate I am getting about 1200-2400 annual cash flow. That seems low to me and a bad year can wipe that out quickly. What do people consider a good annual cash flow in houses in that price range?

Thank you