ECF registered suppliers, and almost any other larger online supplier. I have yet to have a problem with any. As far as shipping, with the possible exception of bulk nicotine and pg/vg, most suppliers ship either 1st class or priority mail. I know, because for me UPS and FedEx deliver to my house but I have to go to the post office to pick up mail, so I'd be happier if the didn't mail everything.
Oh, and most suppliers have free shipping above a certain (variable) dollar amount, and since it is almost all mail, being in Hawaii shouldn't matter.