The only thing that comes close to an eInk eReader that can handle PDFs well is the Kindle DX ($380). Do not go with a smaller format reader and think you can convert PDF articles to ePub. It turns out really badly - unreadable.
Back when eReaders were the big new thing, many companies were going to come out with a large format reader. PlasticLogic was going to come out with their Que reader, but it was delayed multiple times and cost something like $600. It was dealt a quick and merciful death.
The only sensible options today are the Kindle DX or a tablet. I read plenty of journal articles on my Honeycomb tablet, and it's really not that bad. Certainly not bad enough for me to drop $400 on a dedicated paper-reading device.