Over the past few years, we've seen XJS prices started to rise. Several factors seem to be driving this - the fact that there seems to be no end in sight to the E-type price rise; the fact that many of the worst examples have been weeded out; and the fact that time has been kind to its shape (certainly kinder than the press reception was at the launch... but then how do you replace the E-type?). It's still hampered by a chronic thirst for petrol, but as a classic proposition, this is slightly more bearable as mileages are generally very low. Top of the pile is the XJR-S, which is often seen on a dealer's forecourt for £17,000, while the later 4.0-litre XJS convertible will now set you back more than £15,000. As a rule of thumb, the later models seem to have held their values better than early examples - but there are always exceptions to this. You should be able to get a good one with a few jobs on the 'to do' list for about £3000-£5000. As always, rust is the major killer of XJSs, while V12s are hard to service due to the engine being pushed up against the bulkhead (making it hard to change spark plugs on a couple of cylinders). Parts support is pretty good and the club seems to be slowly waking up from a few years of stagnation.