Building a duplex on a 7,000 sq. ft plot of land?

[Sherman Dunn]

I have found a plot of land for $7,000 in an area that is not the best, but I know it very well. It is 7,000 sq. ft. and I have an idea to put a 2/1 duplex (2bd 1ba) in each unit. The area will allow rents between $850 and $900 which will give me about a 10-12% cap rate and nice cash flow monthly. I have gotten a ballpark range quote from a contractor that whom I know does very good work, and I’ve even done work with him for 100-125k. Has anyone tried this before? And is there anything that I need to beware? The plot is in town and all utilities are existing in the servitude. All replies are welcome.