We find the same with digital or video cameras. We opted for some very simple second hand Nikon Coolpix digital cameras which cost under a fiver each from Ebay, and Sony flip camcorders from the Argos Ebay outlet.
We've bought around 10 Olympus VR-340's in the last year or so - the teachers love them. They don't blow you away picture quality or build quality wise, but they're pretty good and none have broken yet *touches wood*
I bought Lumix DMC-S3's, specifically because they were the cheapest I could get without AA batteries. The dedicated batteries last longer and in a year, none have gone walkabout. We got three for every classroom - one for the teacher, one for the TA and one for the kids to grab whenever they want - and have had no lost batteries (have lost around 80 AA batteries in the same timeframe) and none broken (jinxed that now). They have lost chargers, but as they had three cameras in every class, I only issued one charger, so I do have a stockpile at the minute. They use mini USB sync cables, but generally users seem to prefer to take the SD cards out and lose them :p . I bought the cheapest 2GB cards I could, so there's a nuisance value, but not a massive cost. We turned the resolution down, as the pictures are generally only viewed on screen or printed 6x4, so quality is fine - also saves room on the server and encourages them not to store thousands of photos before they download them.