I supaguarded my Vito Sport last night Coincidence.
Is it worth it? - NO NO NO NO NO NO NO
Dealers pay about £20-£30 for it plus application. They then retail it for upto £299. Massive profits. Here is the thing though, google ebay for Supaguard and you should be able to buy the sponge thing for £20-£30. Thats what i used last night and it was no more difficult than a normal polish.
Does It Work - Yes, in the main it does protect the paint better than normal polish and i have seen cars after 3 yrs with it on and they do look better. I will report back on wether i dont have to polish it again for 3 yrs, we will see.
If i was you i would do her a favour and buy one off ebay then offer to apply it for her in return for, well she will owe you one.