You might want to check out the enTourage eDGe. Not sure if it runs Xournal, but I have seen mention of it in the forum: http://www.entourageedge.com/forums/forum.php
You would want the big eDGe, with its 9.7" e-ink screen and 10.1" Android screen. New, they are over $500, but you can find them used on ebay or Amazon Marketplace for under $200 (or, more realistically, around $300). Just make sure you're not buying a Pocket eDGe (6" e-ink and 7" LCD) -- not that there's anything wrong with the PE!!
Here's a link to some videos: http://www.youtube.com/view_play_lis...ACD88BB53D6385
You'll want to know that the company may be in trouble, but they are still supporting their products. Check the forum (link above) for real user reviews.