When I purchase an existing online business, I look for cash flow over the past year and where the money comes from. I want the sources to be more passive so that it does not take a lot of my time. Also, typically I will make an offer that is 18 – 24 months of profit so that I know that I will get my money back within the next two years. I hope that helps!
Residual income is the amount of net income generated in excess of the minimum rate of return. Residual income concepts have been used in a number of contexts, including as a measurement of internal corporate performance whereby a company's management team evaluates the return generated relative to the company's minimum required return. Alternatively, in personal finance, residual income is the level of income that an individual has after the deduction of all personal debts and expenses have been paid.