The purchase price plus whatever capital the business needs in order to stop being marginal, and around them due diligence, legal, accounting and the published application charges.
Budget for the business you are creating, not the one you are buying
The Department of State publishes the applicable application charges, which should be confirmed when the filing is made. Treat the purchase price as capital at risk rather than as a status fee. Where the marginality analysis depends on adding attended services, contracts or equipment, that additional capital is part of the plan and part of the investment, and it should be budgeted rather than hoped for from first-year profits.
Around those figures sit the costs of proving the case: an independent review of the seller's records, a valuation, U.S. counsel for the purchase agreement and escrow, accounting advice on the structure, and the assembly of a source-of-funds file. Finally budget working capital for a first year in which the business is being changed rather than simply operated.