I'm a 399-er as well. My mom has that unit now -- I only send her SOME of the books that I read

I installed a replacement battery in it, this past April.
I'm using the full price K2 ..... can't for the life of me think why I need a K3, but I might still get one (after my current fiscal crises get solved). I still love my K2! Great device. Even just for a delay in a grocery store checkout line.