I went for the 3 months option.
It is a one off payment for new accounts only, at this time.
Hence once your account is Vip'd and it runs out, cannot top up again with vit.
This may change though in the future, once its seen how it is received.
I can loan you the difference if you need some vit:) There are two types, normal Vip and Ultra
One could i guess make a daddycosmic1 account and xfer things across from old account, all depends how attached one is to ones avatar:)