cool, anytime. Just hope you can find a reasonable device that has most of the features you need. I know many people loved their PRS600 from Sony and it does have an SD card slot as I recall. It also has side lighting for reading in the dark.
Whoopsie, it's the PRS700 that had the side lighting not the PRS600, my gaff, sorry about that one. 
Link to Sony page about the PRS700:
http://www.sonystyle.com/webapp/wcs/...62069#features
The PRS600 did have clarity issues due to the touch layer but not everyone is bothered by the slight blurring/fuzziness it introduced.
I am unsure of the max SD card size though I would think that at least a 16GB card could be used. That is just a guess though. I would hit the Sony site to see if you can find the last firmware update to see if it mentions the capacity limit for SD cards.
Something to remember for the PRS600, when Sony stops support a product they STOP supporting it. I have used a Sony Clie for about 8yrs and then they dropped the Clie lineup that was it, done no more nothing.
I'll peek around to see if there is anything else not mentioned so far. But to be candid for your budget you might have found the sweetspot between compromise of features and your needs. Nothing will be a perfect fit and we have all had to make concessions of our own.