For your reference....
The best tip I can give you is ship Expedited or Express. I always prefer UPS as I like receiving my goods in less than 3 days instead of the normal 14 - 20 days via USPS. This way you will not pay any brokerage
fees. I still have to pay gst & duty, but zero brokerage fees.
Last time I ordered some GBB mags from Airsoft GI they labelled them as samples, put a total cost of 0.00 and I paid zero in brokerage/gst/duty. The order was under $100 and UPS defaults a $100 insurance on EVERY package, declared or not. So if they went missing anyway, I'm covered.