The most conservative approach, often used to value stock for buy-back purposes is that share value equals shareholder's equity divided by shares outstanding. This give no value to future income vstreams.
Typically small businesses can be bought for something in the range of three to five times average cash flow from operations over the past three years. Absent some significant cash flow influence (e.g., major capital project, rapid growth, etc.) this is the best measure. If the business is growing rapidly, the price would be at the higher end of the multiple range.
Operating income can be used as an alternative to cash flow at the same multiples. Assuming this is a partnership or "S" Corporation, after tax (net income) is meaningless because of the pass through rules.
No value should be based on "future projections" unless there are contracts in place that would assure achievement. Also, do not accept CPA's "restated" income statements as a basis for value unless you know that the costs that they eliminated are gone forever. Finally, if you join a partnership, answer these two questions; Will you add more revenue than you cost? If not, why do they want you to invest?