I acquired a 2007 Casita
Spirit Deluxe last year and the prior owner was quite religious about maintaining all the manuals and paperwork. In 2009 he replaced the toilet valve ($34.19) and in 2017 it was replaced a second time ($43.43). The toilet has worked perfectly for me over the past year.
For the prices you quoted for the warranty, I would pass....
Once upon a time I worked in retail and the warranties were an EXTREMELY LUCRATIVE
money maker for both the store and for the sales associate.
I was always amused when purchasing appliances and cars that, after extolling the virtues and reliability of the item, the sales associate would switch gears to sell a warranty under the premise that the item was sure to fail.