Just how relaible are manufacturers estimates of bulb life? I only ask because I'm trying to figure out whether I'd need to get a spare bulb if I get a proejctor, or whether the bulb is likely to last until I think about upgrading to something new. For example, I think i saw an estimate for the Sanyo Z2 of 3000 hours. Assuming that the average film watched is 2 hours long, that means you could watch 1500 films. If you watched 1 film a week that means the bulb would last about 29 years. Is that remotely likely? Or are the, at first glance, rather expensive projector bulbs, actually remarkable value for money?