Here's a tale for those who like their use of technology to be bulletptoof.
In 2001 I bought a Toshiba P4 projector (below) which at £3000 allowed me to travel from school to school to do training. Back then you couldn't be sure that the school's only projector was not already in use. It cost money that hurt: that amount could feed the family for a year. To ensure (sic) that we would starve for another month I bought a spare bulb (£350). That would make me bullet-proof, but by 2012 the projector was still working well. After a few attempts to sell it I got £65 for it.Bah! By the way, I also learned from a good source (the lovely Nigel Steljes in person) that the warranty on the bulb would have lapsed by now. So if the bulb was faulty at birth, buying a spare ahead of need does you no good.
WAS FOR SALE, NOW SOLD:
TOSHIBA PROJECTOR LAMP UNIT TLPLP4 for the Toshiba P4 projector. Brand new in box. The unit is very easy to replace by unclipping a cover. It simply screws into place so you don't have to handle the UHP bulb itself.
This is the genuine Toshiba replacement lamp which I bought at the same time as the projector. It's never been used or damaged. Sells for £150 on ebay.co.uk. Toshiba TDP P4 TLPLP4 TLPLP4 - this is what retrospect says wasn't a good idea to buy:
Lamp spec: 1100 ANSI Lumens; 2000 hour life; 120W
The projector looks like this (this lamp will fill fit some other models). It's tiny enough to fit in a laptop bag and travels in my hand luggage.