I unexpectedly got both my tax return AND my health insurance refund this weekend so I was finally able to go shopping!
Guidebooks:
-Fatal Frame IV Wii
-Hotel Dusk DS
-Card Hero DS
-Super Mario 64 DS
-New Super Mario Bros. DS
-Mario & Luigi GBA
-Wario Land 4 GBA
-Pokemon Puzzle Challenge GBC
-Custom Robo N64
-Slime MoriMori Dragon Quest GBA
Games:
-Napple Tale for Dreamcast - Paid a bit more than I wanted to, but it's CIB with spine card.
-Racing Lagoon for PS1 - Squaresoft racer I heard was cool. 500円.
-The Amazing Spider-Man: Lethal Foes for Super Famicom - Usually goes for 5000-7000円, I found it for 3500円!
-Shonen Ashibe: Goma-chan no Yuuenchi Daibouken for Super Famicom - Seal Platformer?! 300円, what the hell. :lol
-Magical Drop 2 for Super Famicom 
-Mario no Photopi w/memory card for N64 - Strange photo-editing game featuring Mario.
-Majyuuou (cart only) for Super Famicom - I've seen a CIB copy of this at a store near my office for 16,000円 (about $160) that has been MOCKING me with it's expensiveness, but I found this cart-only copy for 1500円 today.
-Pocket Monsters Green for Game Boy - Suggested by a fellow GAFer in my "What should I buy before leaving Japan" thread (
http://www.neogaf.com/forum/showthread.php?p=19956666#post19956666). 210円!
-Custom Robo GX for GBA - Japan-only release. Only 500円.
-Black Game Boy Micro Console - Only 3000円!!
-Gamera for Game Boy - I've been searching for this one for months and I finally found it today. Not too expensive to boot!