problem is that the smaller cars tend to hold their value longer as more peole want them because they are cheap to run and insure

the bigger cars are cheaper for exactl the opposite reasons, they cost shed loads of run and fix if they go wrong

middle of the range is where you need to be, get one in a boring colour and it'll be even cheaper, went to the auction years ago to buy a focus and the silver lx's were going for £5k and we bought a ghia with all the trimmings, in blue, for £3k

you'll be able to pick up a late shape mk4 for that money comfortably, but make sure you enquire as to what a zetec s will cost to insure before you buy one or go for something like a boring focus/astra/megane/etc