This was suggested and accepted when we got rid of fly and wanted to give the entire server fly for an hour or so if someone was to donate for it. Then we did fly notes, I wouldn't mind adding fly notes to a vote crate or something and making them extremely rare but we need to keep donations for ranks worth something at least.
This is fine for me, rare limited time notes are okay.
This is okay with me as well, because as long as it's adjusted with the economy so it's expensive and perhaps has a limited stock per day/month/week it could work,
But I'm a -1 on the original suggestion. The main draw to Ultimate is /fly, and I feel that reducing the price and selling that one perk would not only lead to misunderstandings and confusion but also less donations to Ultimate in general. I also think it's kind of silly to act like you need /fly. It's only usable in Towns, which honestly means it isn't really useful in the long run. No one needs /fly and it doesn't give many advantages anymore.