Jez:
Since the work is for people with vision problems I could make three suggestions....

1) If you a doing a small service type project where it is a one shot or short run type of project you should consider getting a manufacturer to dontate new product to the cause <big>all on the name of generosity for the good of humanity.</big>

2) Are you sure LCD displays are the best for hard of seeing people? Possibly an LED display would be better.

3) Maybe this application is one best dealt with the user interface being other than a visual one. Consider a voice out scheme, a vibratory method, or even a system of tones.

Michael Karas

PS....Used LCDs are almost certainly going to be older technology that has poor contrast. I would look strongly at the latest stuff becasue of much higher contrast that the LCDs can be made to do these days.

MJK