go to ebay and type in "Mango". It provides mango trees from Florida, thus eliminating the problems with shipping from Hawaii. If you type in "Mamaki", you get a Hawaiian grower who ships. While he does not now have mango, you could contact him.

Thanks so much for your suggestions, I have a number of Florida condo mango trees, but none of the state-side nurseries carry Gouveia or Rapoza, which from descriptions on the Internet seem like particularly outstanding mango varieties. I contacted the eBay store, Suncatchers of Hilo, who carries the Mamaki teas, and he referred me to Plant It Hawaii. Plant it Hawaii referred me to Royal Palm Enterprises. IÂm trying to contact them now.
I would be happy with buying or swapping scion wood for Gouveia, which probably isnÂt still under patent, if they were still dormant and graftable. IÂve had good luck grafting apple trees, and a few stone fruit. However, your mangos probably are blooming now, like mine. The regulations for shipping leafless scion wood shouldnÂt be too different from shipping dormant plumeria sticks. But I could be wrong.
The link below has an interesting video on grafting mangos, toward the bottom of the page.

Here is a link that might be useful: Veneer Grafting