You can pick up portable flowers at any ABC Store / Longs.

I do know of a couple who lived in Hawai'i for about 10 years, then moved back to Mass. They took back with them a plumeria seed/shoot. Planted it during the summer and dug it back out every winter and potted it inside near the heater. In two years, they had plumeria growing in Massachusetts, of all places Was very shocked to receive a plumeria flower on my last visit up.

Some of those flowers do have agricultural warnings on them, but I doubt anyone follows them.

Here's the ABC stores' website that lists some information about the seeds/shoots:

http://www.abcstores.com/browse.cfm/2,3.html

You could probably pick them up at Lihue Airport, but it's been awhile since I've been up there.

aloha