Have you looked at the iPad? It's a bit pricey, but the size is great for reading comics. The Pocketbook IQ is 7 inches, but it's pretty cheap (around $150, I think). I haven't read anything about how good it is with comics, yet.
No colour e-ink yet, unfortunately. I would also love a colour reader for my comics.
You can use calibre to convert your cbr and cbz files to epub (I do that with my manga, which I read on my PRS-505.) It's a free program:
http://calibre-ebook.com/