What sort of car do you need? Does it need to be a limo? How many people?
My uncle drives for a number of high profile people, and has access to their cars at all times and has done similar in the past. Not sure of the rates.
At the same time, if you just needed a half decent car for one person, I drove my cousin to his wedding in a brand new 6 series, complete with the ribbons and decorations?