As my colleague mentioned, these are terms of art common to a number of intellectual property statutes, whether we talk about “commercial scale” or “distribution” in the Copyright Act. We never really quantify what “distribution”, “sale”, or “possession for future sale” mean. This is usually left to the court, because on a case-by-case basis, five may be commercial, if it's a valuable product, or ten thousand could be commercial.
So to put it in a regulation, be specific, and give guidance to the court might actually work against it.