I'm not sure I would call any of this stuff rare - maybe hard to find - but it's the "rarest" I have:
Manilla Road - Open the Gates CD (Digi)
Manilla Road - The Deluge CD
Iron Maiden Castle 2-CD reissues - I have IM, Killers, PoM, Powerslave, SiT, SSoaSS, NPftD and the 2-disc Best Of The...