try Future electronics for the L298's....
The Schottky's can be cheap ones if you don't foresee large motors.
You really might want to investigate the Atmega solution; in a sense it just means that instead of plugging into the Arduino baord itself to get the control signals, you put the Arduino chip on the stepper shield itself.
With the L297 you need enable, dir and step pins for each motor (9 Arduino pins), all of which could be boiled down to one pin: Serial RX. That makes your Arduino relatively free to do other things. The L297 code is not that big of a deal.
D
PS: what is the license on your files?