It really depends on how much you value the appearance of your vehicle. Let's use XPEL Ultimate Plus for example, from factory, it already has a hydrophobic top coat to add some beading effect when water hits it.
If you know basic detailing skills, or have a "can do" attitude, I would recommend you buying a high end retail ceramic coating, and then applying it yourself. I would personally recommend Gyeon, as their products are very user friendly, and forgiving in case of any mistakes (high spots for example).
What I've done on my personal vehicle is the following:
- installed PPF on the entire front end and rockers right after possession (XPEL Ultimate Plus)
- did a light single stage correction
- applied a one year coating (in this case, Gyeon Pure)
- every time I hand wash my vehicle, I spray a product called "Gyeon WetCoat", this is basically watered down ceramic coating, and you apply it to a clean, BUT, wet surface, then you rinse off and dry
- then once a month, or whenever I'm bored, I'll manually wipe down my vehicle with Gyeon Cure, which is like WetCoat, but a bit more concentrated, and takes a bit more time as you are applying by hand with a clean MF towel
Following this method, it has given me the results of a five year coating but at a fraction of the cost. As long as you maintain your coating with any product that contains SI02 (the main ingredient in ceramic coatings), you'll never need to re-apply your coating.
YMMV, but this method and combination has worked well for my personal and families vehicles.