So far I've used .pdf, .rtf, .txt, and the Sony formats (.lrf, .lrx) for ebooks, .jpg, .gif, .png, and .bmp for pictures, and .mp3 for music.
With regards to the non-Sony ebook formats:
PDFs can still be scaled with the zoom function on the PRS, albeit only if the reader recognizes the text as text. In RTF, the reader recognizes the metadata (Author, Title) that MS Word saves, so it's far easier to organize like the Sony formats.
For pictures, I chose a random assortment of comic strips from online, full color 6-megapixel digital photos, and non-animated gifs (animated will apparently crash the PRS). The conversion to grayscale is fairly good and I can still see fine details for all images. The larger the file, the slower it loads, but that is to be expected. Photos of written material are perfectly legible, too, albeit dark. One suggestion I would have is that you rotate the pictures before you load them so as to maximize their size. Alternatively, you can rotate the display (via the PRS settings) to landscape.
As for price, it was whatever Best Buy sells them for. I'll have to ask my parents if you really want to know.
I'm running Vista Premium (32-bit), so the included elibrary software kept crashing until I disabled the DEP for it. I'd suggest joining Mobileread.com in order to employ their fora.
Most that are profound would choose to narrate tales of living men with nouns like sorrow, verbs like lose, and action scenes, and love – but then there are now some, and brave they be, that speak of Lunar cities raised and silver spheres and purple seas, leaving us who listen dazed. -- Irena Foygel