Doesn't matter really. How you sell it and what's in it is far more important than the length. You need to nail the sales process and the content - everything else is of very minor importance.
This attitude is more obvious with screencasts. Even 30 minute screencasts can sell OK at $9.. and the amount of effort to put that together is far less than even a, say, 25 page e-book. You just need to hit the right stuff.
All that said, my basic investigations show that in the general programming world, books of < 100 pages tend to go around $9, books of over 200 pages tend to be > $20. But this is all very arm-wavey.
This attitude is more obvious with screencasts. Even 30 minute screencasts can sell OK at $9.. and the amount of effort to put that together is far less than even a, say, 25 page e-book. You just need to hit the right stuff.
All that said, my basic investigations show that in the general programming world, books of < 100 pages tend to go around $9, books of over 200 pages tend to be > $20. But this is all very arm-wavey.