When money is tight, dedicated
anything is usually a bad idea. However, there's always the liklihood that you already have a device you can use to read e-books (a cellphone, PDA, or computer), and therefore do not need a dedicated device just to enjoy e-books.
I can afford a dedicated device, strictly speaking... but I prefer to spend my money on other things*, use my PDA--and maybe, someday, my cellphone--to read literature (and do many other tasks as well), and save my money.
Since small electronic devices like cellphones are becoming pretty ubiquitous, there's no need for the economy to impact anyone's access to e-books based on needing a device. If you can afford a cellphone, you can afford an e-book, and you're already set up to read it.
*Ask me about Valentines day! No, better you don't... for propriety's sake, I'd have to leave out too many of the good details!