I’m aware SBIR funds can only be used for work done in the US. How about purchasing research material (e.g., specialized reagents, mouse tissue, etc.) from overseas? Especially if those material are not available anywhere else in the US?
If there are no suppliers for the research materials available in the US, you can include them in your research proposal/budget. But you will have to provide supporting evidence to justify that these purchases cannot be made within the US and are essential to the success of the research. A lower price abroad when compared to a US supplier, however, is not a valid reason to purchase materials from abroad.