Yeah, that is a tough question. I spent this afternoon virtually shopping for a multifunction device to add to my gadget collection. My main function for it is to read ebooks, of course.
I looked at the Asus T91, the Viliv EX70, the Archos 9, and Always Innovating's TouchBook. Once we figured out that both MS Reader and Mobipocket reader can be coerced to work in WINE (a way to make some Windows programs work in Linux), that opened up more possibilities.
The TouchBook is the cheapest, and also has the form factor I want (tablet). At ten hours of battery life with the keyboard half attached, it's a definite contender.
And then of course there's always the anticipation of Astak's Spectrum model when it comes out.
I already know I won't be getting anything until tax time next year. Student status does have a few perks...and they show up in refunds.