Filing fees at more than one stage, published in the USCIS fee schedule; administrative or subscription fees where a pooled project is used; legal fees weighted toward the source-of-funds work; and professional costs for accountants, translators and diligence.
Count the second stage in the first budget
Investors commonly budget for the capital and the first petition and forget that the process has a second half with its own filing and its own evidence. Fees for each stage are published in the USCIS fee schedule, Form G-1055, and should be read at the time. Pooled projects usually charge an administrative fee in addition to the capital, and it is often non-refundable, so its treatment should be understood before signing subscription documents.
Legal fees are substantial because the source-of-funds work is substantial, particularly where a business sale sits behind the money. Independent commercial diligence on a project is a separate expense that many investors skip and should not. Accountants, translators and, sometimes, valuers complete the list.