Cedar siding, paint or stain ???

Hello all, I am installing some windows for a client and he asked me a question that I can not answer, (this is not my field) this client is building an addition, the old part of the house has cedar siding that is painted the paint is peeling and needs to be painted again, for the new part they went with cedar siding also, the question is, what they should do, the client likes to put a good dark colored stain and maybe paint the old a dark color to match, or blend it in. the contractor doing the work told them it's going to be hard to blend it all in with paint and stain, and he suggested they rip of all the old siding and replace with new, but with labor and material it's around $4000.00 or paint everything one color, they don't want to run out of money before the project is finished, any ideas on what the best thing to do.
thank you