[delphin]

You didn't say if you are looking for an e-ink device?

If so, I agree with the others who have pointed out that the 6 inch e-ink device that comes closest to meeting all your listed requirements, and that has by far the best handling of PDF's, is the Sony PRS-650.

The PRS-650 is in short supply now, so don't be fooled by the outrageous prices the scalpers are asking. I paid $199 for my PRS-650 a short time back, which is still a little over your budget, but probably worth the difference if you want good PDF rendering and an SD card slot.

The PRS-350 has a slightly smaller 5 inch screen, and doesn't have a SD card slot, but it also has good PDF handling, and the price has recently been reduced to $129.

The problem with PDF's is that they are usually formatted for a full sized printed page, and are hard to make look good on a small e-reader screen.

Sony uses official "Adobe Reader Mobil" from Adobe, so it does one of the best jobs on PDFs for a portable device.

Unlike most other readers, the PRS-350/650/950 readers will try to "re-flow" your PDF's so you can read them on a smaller screen. (most other portable e-book readers do not do PDF re-flow)

If your PDF's aren't too complicated, this works fairly well.

Some PDF's with complicated graphics and text don't re-flow well, and then you have the option of keeping the smaller font (which turns off reflow) and then 'zooming in' instead. This keeps everything in the right place, but you have to pan around to see everything on the page.

It's still tough to deal with material formated for a larger screen, but if you find a document that is hard to view on the PRS-350/650/950 readers you can count on the fact that it will be even WORSE on the Kindle, Kobo, etc.

As has been said, the BEST option is to find books already formatted in EPUB format (which the PRS-350/650/950 also handle really well).