Techjapan reports that Toshiba is coming out with a line of Tablet PCs: the Dynabook R10 / 170L7. Low cost here would mean 19500 yens ($185! Is this really true?)
The screen swivels to switch between normal mode and tablet PC mode. It comes with Windows XP Tablet Edition 2005 and a bunch of software for kids (it is apparently aimed at elementary schools… that tells you how cool they are over there).
Quick specs: P4 Celeron 1.4Ghz, 512MB, 60GB HDD, DVD, 14″ XGA LCD, Wifi B/G, 28 x 289.7 x 36.9 ~ 38.4mm (W x D x H), 2.8Kg.