A gift to the U.S. government and a processing fee, in amounts stated on the official programme site, plus ordinary professional costs. Whether any part is returned in any circumstance must be established from official material before payment.
Establish the refusal outcome before the payment
Because the payment is a gift rather than an investment, ordinary commercial expectations should not be assumed to apply. A gift is not a deposit, not capital at risk in a business, and not something that carries a return. The single most important commercial question is therefore what happens to the money if an application is refused, withdrawn or abandoned, and the answer must come from the government's own published material rather than from an intermediary with an interest in the transaction.
Amounts should be read at the time of acting, since figures quoted elsewhere may be stale. Applicants should also budget for legal fees, document preparation and translations, which are payable regardless of the outcome and sit outside the programme's own charges.