I'm a big PDF hater (for a multitude of reasons), but I have bought a PDF or two before. In any case, though, I'd never pay more than 25% of the print price (maximum, and likely a whole lot less).
OH i agree Auld. piracy sux, but its a reality, and it pays a heavy toll on the guys who are trying to make it with good quality stuff.
All I was trying to say is that a side effect of it is that its the nail in the coffin for the crap content.