Carbon cleaning in Toronto and surrounding area?

The lease is up on my S4 next year and one of my uncles is interested in buying it. It currently has about 40,000 km (about 25,000 miles) and I figure it’ll probably need it at some point in the future. Anyway, I wanted to give him a heads up about it, and a rough cost so he’s aware before he decides to buy it.

Does anyone have a ball park idea for the cost of cleaning and what intervals it should be done at? As I mentioned I’m in Toronto and my uncle lives in Pickering (a city east of Toronto).