I absolutely discuss the pricing with Clients before I see, and again when I see the vehicle/s, and then make up the Invoice with the price quoted (so I wont forget either), and then review it when done, adjust if necessary, and give it to the Client on pick up.
They can also see all my pricing on my Website, and I give them another business card which has my website address on it.
I also make sure they know exactly what I am going to do, and if they are standing in my garage, I will show them the products I am going to use, if they want to know this.
I also if they want to, update them nightly, etc., on the progress, send a few pics if wanted, so there is absolutely no surprises for either of us later.
Some of my Clients live close by and sometimes come by to see their "baby" getting the SPA treatment, and I am ok with that as long as they dont interrupt too long.
At least out here, a lot more people are wanting to get "educated" on how to Detail a vehicle properly, and after talking to me or seeing my work, they tell me horror stories of friends or even themselves after going to the "Dealer", etc., for Detailing services..
Again, out here, since almost everyone is very computer-android-blackberry-texting, etc., literate, I use the quickest way possible to keep them apprised, and therefore, never have any issues when they come by or I deliver their"baby"
Dan F