Sadly, it's available, but at 3-4x that price, with poor battery life. (A tablet would do it.)
If we're wishing, I want a US Letter or A4 sized device with color, a reflective screen (like e ink), 300 dpi (including the color), at least 12 hours of battery life, AND a scanner built into the bottom so I can just set it on top of a page and it will pick it up.
Heck, I'm wishing, so I'd also like it to be only 1cm thick, and while it needn't be flexible enough to roll up, it should be slightly flexible to fit into the spine of a book I want to scan a page from. This should make it more durable, as well.
Heck, might as well throw in cellular connectivity to the internet as well, and pen and voice input. Since I'm only wishing.