X68000 - preferably Expert or XVI. Maybe Compact.
PC-88/98 - FA, SR, MA, or VA2
Shantae and the Pirate's Curse - Japanese
PC-98 Keyboard
Sharp X1 
AIZA - Obviously if I can find it.
46 Okunen Monogatari if I can find it.
Slayers 98 if I can find it.
PC-FX GA - PC-98 Dev kit
Xanadu Complete Collection
DragonSlayer Chronicles
I love Camazotz - Xanadu Fanzine
PS2 Games: Sega Ages - Gunstar Heroes, Panzer Dragoon I & II, Gitaroo Man, Ys V: Sand City of Kefin
Popful Mail - PC-Engine
Popful Mail - Mega CD
Yasunori Mitsuda - Our Millenial Fair Chrono Trigger and Chrono Cross Arrange Album?
Dark Souls I & II Artbook
PC-9801-86 C-Bus, depends on how expensive. 
WonderSwan Color



Akihabara BEEP
Nakaei Building (basement)
3-9-8 Sotokanda, Chiyoda-ku
Tokyo 101-0021