The published gift amount to the U.S. government and the processing fee, at the stages the official page describes. Recoverability, if any, is set by the official terms; the gift should be assumed non-refundable unless the page states otherwise.
Two program amounts, one question about refunds, and private costs outside both
The official framework lists an individual gift amount, a separate corporate amount that does not apply to a retired couple, and a processing fee, with the page describing when each is due. The gift is not placed at risk in a business, is not expected to be returned and is not an investment in any sense used by EB-5 or E-2. Whether the processing fee or the gift is refundable if the application is refused or withdrawn is a question the couple must answer from the official terms before paying, and the safe assumption is that neither is.
Outside the program sit the private costs: advice on reading the terms, translations, travel and housing, and Canadian tax on the sale of the herd and quota, which is owed regardless of what the couple decides. Write a three-column budget, gift, fee, everything else, and re-verify the two program figures on the day of payment.