How do I figure out what my share of the business is actually worth?

The starting point is whatever specific valuation formula your written partnership agreement may already specify, if one exists, since a pre-agreed method removes much of the uncertainty and potential for dispute. Where no such agreement or formula exists, fair value is typically established instead through a professional business valuation, a formal appraisal process conducted by a qualified valuation expert, which realistically costs somewhere between $5,000 and $25,000 depending on the complexity and size of the business involved.

This valuation expense represents a genuinely significant and unavoidable part of the overall economics of pursuing a partnership dispute, and it's a common, practical reason that smaller partnership disagreements frequently settle for less than a strict, formula-based calculation of ownership interest might otherwise suggest, since both sides are often weighing the valuation cost itself against the disputed amount at stake.