What Return on Investment (ROI) is realistic?

If we purchase a $50,000 3 bedroom / 2 bath home, add the closing cost plus minor repairs, we end up with a $60,000 total investment. Taxes and insurance will be about $2,000 for the year. The home can be rented for $900 per month, or $10,800 per year minus $2,000 for taxes and insurance and 10% or $1,080 for management that will give us a net profit of $7,720 per year or 12.8% return on investment per year. Also keeping in consideration we are buying at the bottom of the market and you can be sure that the $60,000 house will be worth at least $120,000 in 5 years or less. They were selling for $240,000 a couple of years ago - we cannot assume that the market value will go that high again soon, but $120,000 is absolutely realistic and would be a level still affordable for people with middle class income.