A new Rolls Royce will cost between $300,000 and $400,000.
A used one from the 70's to 80's ish is in reality quite affordable. Not even the Rolls is immune to depreiciation. About 6k to 10k for a 1970's to 80's silver shadow. 1990's Rolls are still quite expensive. 60s and older Rolls will be 100k plus for one that does not need major restoration, and many owners will not part with their Rolls Royce.
Beware as parts and maintainence will be VERY expensive. Be careful not to go to a garage run by a crook who will wreck your rolls royce, as not many people know how to service them.
If you are an average guy, your best chance at getting one that is affordable is the RR Silver Shadow I and Silver Shadow II (the latter one will be a little bit more money)
Any RR Phantom from any year will be unafforable for the majority of people, and they are VERY rare.
Please do not modify/hot rod/paint it ugly colours on your Rolls Royce. It is meant to be a dignified and elegant car, not a god-awful some pink racing car with flames on the side and fuzzy leopard-pattern upholstery.