Unless you're buying used, I believe the 3308 has been superceded by the 3500 which has the LED backlight which is much brighter. lasts longer and sunlight readable.
Having said that I fly with the 3308 and have had nearly 400hrs trouble-free without changing the bulb. I carry a spare one for when it does need replacement, but changing it out is not a big deal. The trick to bulb longevity is to not have it on full brightness the entire time. I actually find 1/4-1/2 intensity is sufficient most of the time unless the sun is shining directly onto the Sandel from behind my shoulder.
Otherwise it is a fantastic EHSI - able to display anything you could ever want, including maps, tracks, bearing pointers, CDI's, RNAV annunciations, distance and bearing to next waypoint etc.