I also live on an island, and have the same problem getting random items shipped. My workaround is to order from a Marketplace seller listed in the sidebar instead. Normally I avoid them and buy direct from Amazon, but this works surprisingly well.

I've purchased all kinds of 'restricted' things this way, high-power magnets, chemicals, flammable aerosols, commercial-grade fire extinguishers, etc. I think Amazon's rule is mostly based on what can't go by air, since they want all options (ground/sea/air) available. I have no idea what method the third-party sellers actually use but everything shows up in plain brown boxes no problem. Try it some time, and just pay a couple bucks extra for shipping and avoid the hassle.