A common rule of thumb is that a property ought to produce rents of at least 1% of sales price, and this one is marginal. When I do the math, I figure $100/mo repair costs for a small house (including new roof and HVAC every 15 yrs), and you're only estimating $20/mo. In some parts of the country, roofs last longer. But repair costs are very cheap where I live. If you're serious about this, you should put more thought into cost of maintenance.