St Louis - duplex - deal analysis advice

[Hsiang Lo]

I've never done a deal analysis so bare with me :) I'm looking to buy a duplex in st louis for my first rental property. Details:

227k asking price

4bd, 2br 

44k down payment, $1046 per month (includes mortgage, property tax, insurance and mortgage insurance)

2 units and each unit has 2 bedrooms and 1 bathroom, rent per unit is 1100k per month (i think this is the average rent for 2 bd 1 br near st louis university, please correct me if i'm wrong)

NOI: Annual rental income $26,400 (1100*2*12) - Vacancy loss $1320 (28,800*.05) - Operating Expenses $4800 (400*12) - property management fee 2640 (26,400*.1) = 17,640

Cap rate: $17,640 NOI/$227,000 Property Value = 7.7% Cap Rate

Is this feasible or decent? or am i completely off? Any advice would be appreciated :)