Where can i buy a used/cheap sony vaio u101 in Tokyo japan?

wezix,

If you're willing to spend a day tramping around Akihabara's hundreds
of electric shops, you're likely to eventually find what you're
looking for.  However, it's tough to find out what's available without
actually going to see for yourself.

The largest chain of used computer stores is Sofmap, and they actually
have a website where you can search their entire inventory of products
available.  Unfortunately, they have no U101's listed for sale right
now.  The closest thing to what you are looking for is a Vaio VGN-U50,
details of which are found at
http://www.sofmap.com/shop/product/tanpin.asp?PRDT_ID=1501501

The best place to find used computers is without any question, the
YAHOO Auctions, in Japan, but unfortunately Yahoo Japan auctions only
sell inside Japan.

There are a chain company called Hardoff, specialized in used stuffs,
including computers, maybe if you mail then...

http://www.hardoff.co.jp/

Good luck