JR has a store in NYC. The Sony 350 has a 5" screen, but because of the high resolution still it's as readable as a 6". Worth checking out at least! The Sony 650 is a bit more expensive than many other, but a really good reader and I think it would be worth the money if they have it in stock. (It's very hard to find a 650 anywhere now.)
http://www.jr.com/category/office/book-readers/
I guess you could also find a BestBuy or Barnes and Noble and pick up a Nook as well. As non-US people we can't take full advantage of the "buying books on the go", but that would not be a big deal for me. I would get my books in other places (like library and Swedish online stores) and sideload them.
Hope she has checked out the Swedish eLibrary! Really good!
http://www.elib.se/bibliotek/