Coby Kyros. 800x460 screen resolution. 7-inches display. LCD. Resistive touch-screen. Cost around $145.
http://www.amazon.com/Coby-MID7015-A...dp/B0047Q9GT4/
Bad news? You need to root it to take every advantage of it. But it's a hella cheaper than the Nook Color.
Not sure if it's a good pdf-reader because, imo, anything that's not 9-inches or above display is not a good pdf-reader at all.