Is $15,000 to paint old wood siding a fair price?

My house is around 100 years old and I believe it has cedar siding. Two sides are in good condition, but the other two probably need sanding and some shingles replaced. I'm getting conflicting advice from painters who say it's better to paint and siding guys who say it's better to replace with vinyl. I also have a painter who can do it cheaper but usually only does interior work, and I'm wondering if this job is too complicated to risk with him. I bought the house 11 years ago, and the previous owner likely painted it right before selling. I am in the northeast in an expensive area.