The Esterbrook Radio Nib #914 combined with Tachikawa Comic Pen Nib Holder, Model 40 (T-40) is a great combination for drawing.
The nib was found on eBay and the holder on Amazon. The two together were less than $20.00.
The Radio Nib is supposedly the one that Charles Schultz used to draw Peanuts. This nib is long and flexible and easily provides a variable line. It is easy to see why it was Charles Schultz's favorite nib.
The Tachikawa nib is made from wood and has a soft band that keeps your fingers from slipping and makes the pen very comfortable to hold.