You can now pledge/buy Fireforge plastic boxes at ca. 20 % discount (plus postage ofcourse) via their Forgotten World kickstart.
This doesn't include their new Byzantine Auxiliaries, but does include the Fantasy/Bret Pegasi.
IIRC, if you only take existing plastic boxes, they will ship soon after the KS ends. So you don't need to wait until May 2019.
Ofcourse it's a KS, and one that still needs to fund.
-Z