Yes, I recently had a finderscope arrive with a faulty one which was replaced. This is the simple switch on and adjust brightness one.
I do have a fancy one that I quite like. Mechanically, it doesn't look any more robust, but it it much more adjustable. It's the Rigel PulsGuide illuminator. Same thread as the simple version. Comes with yellow and red LEDs - interchangeable apparently. Pulses on and off. Adjustable are:- brightness, period between pulses, length of "on" pulse.
http://www.skiesunlimited.net/index.php?ProductID=4054
http://www.optcorp.com/product.aspx?pid=1639
Price is reasonable.
Mine was second hand with the red LED - came with an Antares reticule eyepiece I bought off an IIS member. Has worked well.
I just want an auto-off on every one of these - I often leave them on and flatten the batteries
