The market for the S3 is on the up. The Jag provides a lovely driving experience and, with flat-floor Sis going for £300k.
The price can be very attractive. Manual roadsters are the most sought-after, but the auto is not bad; it's the only E-type in which we think it works. You’d be looking at £90-135k for a nice roadster, with average cars £60-80,000 and projects £25-40k.
Fixed-heads are £35-55k for a project, £50-70k average, and £60-95k for the best. A full rebuild is about £150,000.
V12s tend to be bought by enthusiasts who understand the greater usability.
Upgrading to the latest ignition systems is popular, as are an electronic fuel pump and injection (using XJS hardware, plus a modern ECU and coil packs).
The result is improved economy (20mpg) and far cleaner running, plus the elimination of hot starting issues.
The most important aspect is the condition of the monocoque, and an engine inspection is always a good idea.
Cylinder heads and cooling systems can be a problem on infrequently used or poorly maintained cars, but they are reliable once rectified.
£1000 per year should cover a full service and sorting the inevitable niggles. An S3 will drive terribly if the suspension bushes are shot, but it's a relatively cheap fix.