I too noticed the price disparity in pricing (or actually a lack thereof) comparing the core books to the adventures. The wizards main page lists PHB as $35 US and the first adventure as $25. One is a 300+ page hardcover and the other is a 64 page paperback. They certainly didn't price these according to print costs, development costs, or any other system I can see. I think a previous poster is right in that the core books are basically sold at a loss and the adventures (the first few at least) are meant to make up some of that loss.
Looking at the WotC site. The first few 3e adventures were $10 and the last few were $20. Guess 4e is gonna be another $5.
Looking at the WotC site. The first few 3e adventures were $10 and the last few were $20. Guess 4e is gonna be another $5.