the Martelli looks good for arthritis (which I also have) found one on ebay for $22 see description below....
[h=2]Martelli Ergo 2000 45mm Rotary Cutter[/h]Cutter fits in a natural hand postition and is engineered for easy maneurverability. Hand pressure points are evenly distributed when cutting. Hand placement requires less pressure when cutting. Great for those with arthritis, carpel tunnel syndrome, tendonitis, hand fatigue, neck & arm pain. Has automatic spring-loaded guard. Flips guard open with finger or rolls open on mat.