Hi nekokami!
I advise you to consider a Compaq/HP Tc1000 or TC1100 TabletPc.
You can find a review of the TC1100 here:
http://www.tabletpc2.com/Review-HPTC1100.htm
and of the TC1000 here:
http://reviews.cnet.com/HP_Compaq_Ta...-20627295.html
You should be able to fetch the TC1100 on ebay for around 800 US$ and the TC1000 for around 4-500 US$.
I used to own a TC1000, and found it reliable. The only real problem was the affidability of the stylus connection. And the fact that it uses windoze of course...