I am an avid fan of photography involving water drops and I have been looking for a product that will help me achieve better pictures with them. I have a seen "The Time Machine" a product that will trigger the shutter at a set time after an event occurs (in this case, a water droplet falling through a sensor). However, it is not cheap and I feel there is a better way to go about it. Does anyone know of a way I can do this? I know of products that will set off the shutter via a flash sensor, but I'm looking for an optical sensor to trip the shutter instead.

I haven't tried water drops my self but have been interested for a while.

Here are some low dollar kits that may interest you.
"HiViz.com Your source for DIY high speed photography."
http://www.hiviz.com/kits/cbp.htm

Dig into this site. It looks like it has every thing you need and or need to know.
The photo gates on this page look particularly promising.
http://www.hiviz.com/tools/triggers/triggers3.htm


Bonus-
An interesting article you may have seen already.
The Comprehensive Water Drop Photography Guide

And lastly-
No help for your request but, I thought the second video here was amazing.
http://strobist.blogspot.com/2009/05/how-to-photograph-water-drops-with-one.html