Get one of these... It's only like 25 bucks.
Besides... Your product representative should have his Oregano nicely packaged in little baggies and weighed. You should have nothing to worry about unless you are buying at a non reputable establishment that is not monitored by the department of weights and measures... OR... If the oregano is actually being weighed by you for redistribution. Then I see why you would not want to have such a device in your "possession" lol.
p.