There is a vanity suggestion box. Modifying the vanitys I don't think will happen.
To take care of the players who have spent more time in the game.. As for what you say about the price, it is relative but not only fuck the entire market but the RP vanitys would no longer make any sense. And what you mean is only for those who make high donations and that would make it cost a lot, NO... many can make large donations, MANY. I would go down step by step, even more with something simple that I will tell you ... If there is a nice object someone else will come to copy it, in time it would be nothing unusual to see it everywhere. The vanity suggestion box is the best for those who want to show their "inventions" many vanities of the game came out of there, such as the Ludicolo Cap. And sorry my english xD