some advice to the op. I didn't look that long, But i couldn't find What kind of protection these pdfs have. Is it DRM, watermarking, Or the honer system?
I think it would also be nice if products were laid out so the eye can more easily see how many pages they are, whats the intended party level, a simple title that explains what the pdf does (if its a adventure or rules module etc) rather then having the pertinent information embedded in a paragraph. You could then soly use the paragraph to talk more about the ins and outs of the product. I think that will increase impulse buying.
I love the art btw.