I have an engineering background and have also spent my life, well, since the age of 17 of course, driving second hand cars. For me it has been a matter of simple economics - my wife gets the decent car, so I have to have an old one!
I am not emotionally tied to a particular make, fuel type, specification levels, engine size or any particular aspect of a car - I need it to get me from A to B safely, reliably and relatively cheaply. I therefore tend to look for cars that are likely to fulfil those simple criteria.
I do however have one unwritten rule. As soon as I get a new (well... second hand) car, the first thing I will always do is check its history for a Cam belt replacement. If the belt has been changed by what appears to be a reputable tradesman and is still within the time and mileage replacement bracket, then that is great news. However, if it is not still within the replacement bracket, hasn't been changed or if I can not find any evidence of a change having been made, then that is a job I get done immediately. I simply consider it to be part of the cost of buying that particular car.
The consequences of a cam belt failure are just too great to consider taking the risk. Unlike most other automotive components the cam belt does not fail in isolation - when a cam belt fails it takes a lot of other things with it. Furthermore, the majority of the parts it takes with it are internal engine components, which means a major strip down and overhaul of the engine - in many cases this will end up with your car being beyond economic repair....at best, it is a substantial garage bill.
The outlay for your cam belt change is peanuts in comparison - yes, it may cost you about £500 (very much dependant upon make, model and age of car) and therefore represents a substantial amount of money for most people, but it's a snip in comparison to losing your car or the repair bill you could face if the cam belt fails.