When the ceramic coating is applied to the vehicle there is more than just the application of the product.
A good shop should be correcting the paint first, which is a task in and of itself on a truck this size. On my truck I had coating applied to the windows, windshield, moon roof, back glass, the trim, the wheels, the tonneau cover, all the plastics, and bumpers. This all comes with application of layers and curing time in between.
I don’t see how any reputable shop could do that amount of work, on a vehicle this size, with that much materials for less than a few thousand. It took 4 guys working on my truck non stop to get it done in 2 days. If a shop quoted me less than a few thousand for a vehicle this size I would get in my truck and leave. If I found the product they used cost $8 a bottle I would get in my truck and leave.
You can definitely buy products online, do it yourself, and see a difference. However, I doubt you will be seeing the full benefits or longevity had it been done professionally.