How long ago did you message him?
If you didn't already know, he takes a bit to answer since he is running FFF all on his own. I still have yet to order from him, but I hear he is an awesome dude and his selection of Myrtaceae is amazing! I would just wait.You can buy plants and other plant materials too.
You might have better luck finding him on Facebook. There he has a page exclusively about Myrciarias. You will find the must currect selections there. He takes lots of great photos of what he's got fruiting. There are some other buy/sell/trade groups you may like on there.
E.g- "California Tropical Fruit Growers", "Acca, Eugenia, Myrcia, Psidium to Xanthostemon all the Myrtaceae", "Plinia, Myrciaria - Jabuticaba, Jaboticaba, Jabuticabeiras ONLY"," Rare Fruit Auctions" (Fruit, Plants, Seeds, and Scions), and "Sale of seeds of tropical fruits"
Fruitlovers will have some rare Myrtaceae, but its best to keep checking because seeds come and go quite quickly. I have ordered from Fruitlovers two or three times, and have had great success with pretty much everything I've purchased.
You could of course make another inquiry on the buy/sell/trade forum here, and certain members here will occasionally have some cool species for sale. You just have to look out for them. There are several members on the forum from central/south American countries that carry rare species as well. Shipping will likely be a bit pricey, but in the end, its all worth it right?!
I will some times order from Tradwinds Fruit. Their seeds are not always the freshest. But buying Myrtaceae seeds from them has always been successful. You usually can only but by the seed with Myrtaceae, Garcinia, and some other rare and recalcitrant seeds. But some packs will give you two or three seeds.
Sometimes you just have to look around a bit to find the more uncommon things.
Good luck finding everything.