I have just been visiting http://www.tokyu-hands.co.jp/shibuya in Tokyo and I need to tell you more about it: This place is an art buyers paradise. I have found the most amazing materials, inspirations and squirky stuff there. I highly recommend floor 1C (party supplies), floor B1A (packing supplies) and floor 5C (sign boards). You will not forget this...even though it is "just" a DIY heaven.