On the FutureBit site the node upgrade shows "SOLD" but if you click the image it says "Both Batch 1 and Batch 2 Kits are back in stock and ship within 1-2 business days."
Is the upgrade for batch 1 available?
The "Add to cart" button is missing which would suggest all the options are sold out. If it's the MCU board upgrade you are missing for a batch 1 then look for a 512MB version of Orange PI Zero (not "plus", not "2") with straight pins soldered in the expansion port. It's nothing FutureBit specific. Batch 1 came with a 256MB version of that MCU board which doesn't have enough memory for running the node.