If you want a high quality spray on Ceramic Wax (not the same as a ceramic coating), Griot's 3 in 1 Ceramic Spray On wax is: reasonably priced, very easy to apply, will not cause white residue on rubber, glass or flat paint surfaces and will last 6-9 months. I use it as a topper (applied over a coating of Griot's Poly wax / synthetic wax) on my vehicles, boat and Lance.
Although I do not believe all of the hype of ceramics, the Griot's product is incredibly effective (protection, longevity and water beading) for a spray on product.