As someone mentioned definitely give
www.mercedesshop.com a try, lots of good experts on that forum. With the help of members on that forum I've been able to not only find the right car but also maintain it properly since purchase.
Before buying an S-Class do a search, you'll find many items that require attention on these cars. If you get one definitely purchase an aftermarket warranty. Many also suggest buying the 98 and 99's as most of the known problems were addressed by the time those vehicles were built.
Good luck with your search. If you have any questions feel free to email me, if I don't know the answer I'll at least be able to lead you in the right direction.