I have 8 XS SDRAM kits available. These include the PCB, RAM, capacitors, and pin headers needed to make your own.
Order here, $14.
I also have some nice Kester 959T no-clean flux available here. US shipping only.
Install instruction are here. Be advised that this is pretty fine pitch soldering so experience is required. I also recommend placing the board into the DE10-nano before soldering on the 3 pin P2 connector to get correct placement.