Keep in mind that there is variation on the number of layers of coating is applied which will impact the price. Ceramic Pro for example has 3 different packages that range from 1 layer of 9H to 4 layers and have a 2 year to lifetime warranty respectively. Packages will range from ~$1000 to $4000+.
https://ceramicpro.com/ceramic-coati...s-ceramic-pro/
Also, as others have stated, prep is the most important step and you will pay a bit more for quality work/experience.
I went with Feynlab for my '19 M5C
https://www.feynlab.com
I paid $1500 for a 3 layer / 10 year warranty application. I chose this product over Ceramic Pro because of its self healing properties...nothing against Ceramic Pro, they've been around the longest and are considered the best, but I wanted the newest tech available.