I don't have any recommendations for but I would recommend against the Gralab 300 clock-face style timer. I currently use one for my enlarger.

1. It is very hard to be consistent. It doesn't click between seconds (no steps) if you know what I mean (at least mine doesn't).
2. Again, consistency & exactness is hard because the enlarger turns on while you are winding the second hand forward. Normally I just twist it as fast I can but when I need to be really exact I work the enlarger power switch and the focus/enlarge knob on the gralab and try to turn both on the exact same time.

3. I definitely like my Gralab way better than not having a timer. But if you can get something digital or with knobs rather than a clock face I think you'll have a better time.