There are numerous ways this is normally done.
The most traditional is to provide for payment under an irrevocable letter of credit, either "sight" or "time", e.g. 30 days.
The alternative is to establish a security interest under Article 9 of the Uniform Commercial Code which each state has adopted (with some variations) which includes but is not limited to filing a UCC-1.
Avvo has some very good business/foreign trade attorneys in New York under the "Find a Lawyer" function button below.
The above is general legal and business analysis. It is not "legal advice" but analysis, and different lawyers may analyse this matter differently, especially if there are additional facts not reflected in the question. I am not your attorney until retained by a written retainer agreement signed by both of us. I am only licensed in California. See also avvo.com terms and conditions item 9, incorporated as if it was reprinted here.