Just an update
Thanks for all the great feedback, what a great group of people in this forum!
Had some time with the Nook today at B&N. What a nice clear screen! It is a much easier to read screen than my experience was with the Sony Prs-600. But the screen was the ONLY reason I took that Sony back, I loved everything else about it. I liked the Nook but my least favorite part of it was navigating with the lcd screen at the bottom. That did not seem intuitive to me. I suppose like anything though I could get used to it. Like the idea that its expandable, and that there are firmware updates for it. Seems like a really good unit on the whole to me.
Next stop was Best Buy where I took another look at the Sony pocket edition Prs-300. Great clear screen, just wish it was 6 inches instead of 5. No expansion, but it was easy to navigate for me, alot like the Sony touch 600 in some ways. No wifi either but as gaston pointed out probably not a real deal breaker for me either.
I also checked on Craigslist as Elton Noway suggested and sent off an email regarding a "mint" condition used Sony Prs-505 for $220 in my area. Will see what happens with that.
Thanks again for everyones feedback.