When I go on holiday with the bikes on my wife's car... the bike locks and security cables are worth more than my car. I spent a small fortune on security, getting cables specilally made up at the chandlers as well as the usual commercially available stuff.
There are days where I think I'm a bit of a d1ck though. My bike is worth over 50 times a FS Halfords special. There is no way I'm a 50 time better rider because of it. And I doubt that I get that much more pleasure either. But it is an absolute joy to ride and I wouldn't want to give it up.