Of regular use, my 40D is still going strong though I just added a 5D Mark II to the stable a few hours ago... so that's about $300/year so far. I do still own the D30 I purchased in 2000 when I dumped Nikon because I didn't like their D1, let alone its price. It is still working strong and on loan to a brother... so I can't say that it is regularly used by myself.
I stopped using it regularly shortly after the 10D hit the market, so it was one of the more expensive cameras (esp. considering it also needed an out of warranty repair). At least four times more, per year, than what the 40D has set me back.
I would have mentioned an earlier Lumix LZ, but a 'rellie' left with it a couple weeks ago when she discovered it was colour-blind (IR converted). As it is summer, we have had a stream of guests and three more converted Lumix cameras of similar vintage slipped through my grasp. The remaining Canon A80 that I purchased new is working fine but I can't bear to use it anymore.
As for longevity, I know that the Olympus C7070 I purchased in 2005 is still running strong for a friend. The CoolPix 880 sitting on a shelf in my basement is also working fine, but I didn't purchase it new and its seen no action for a long time. My son's XT and my wife's XTi are both chugging along fine.
The take-away from this is likely that none of these cameras were 'bargains' and none have been abused. I think that likely has a lot to do with their longevity. Equally so, most were feature-rich except the base P&S versions, but their build-quality was better than average.
I'm hoping that my latest acquisition, plus the m4/3's that preceded it, share this longevity. The great equalizer, time, will be the ultimate judge.