I don't get why you think a 2.0 Mk3 8v will be much more expensive than a Mk2 1.8 8v. There's only 3 horsepower difference and I know which one is likely to be more desirable to a thief. Mk3 is cheaper to repair due to more plentiful parts as it's newer and it will be slower due to being heavier. Why not actually get the quote before jumping to conclusions?
Also how does a 150bhp Mk4 1.8T become less of a risk than a £700 115bhp Mk3 tugboat?