Current shape XJs start at £25,000 retail for a 2009, so you are in with a shout. XF 3.0 275 diesels are easier to find, but there will be confusion with the 240 diesel. 5.0 V8s are great fun to drive and are going cheap. I'm more of a fan of them than of the Phaeton, but a Phaeton is still a lot of car that not many people want, so for not much money (the Bentley Continental is based on it). There is always a market for W221 S-Class diesels. There's even one of them in my local station taxi rank. They seem to have had fewer problems than the previous W220 S-Class. Don’t forget Audi A8s. Most exotic in this class is probably a Maserati Quattroporte.