Sony PRS-300 fits most but not all of your wants. It does not offer the dictionary. Sony and Nook are the only 2 to do local library checkout right now, afaik.
As for a $50 for a light, that's some light

I just picked up 2 lights at Barnes & Noble for my 300 ($8.95 & $10.75) that I plan to try out to see which is better. I haven't had a chance to try them yet, probably the next day or 2. You can see that thread
here.
MSRP for the 300 is $199, and can be found on sale occassionaly for ~$179. There will be others that will chime in soon with even more info for you.