Hi, my parents are making a rare Y trip with VS between LHR & JFK. (They are Oneworld Sapphire but my sister chose Virgin as a gift for them!). Anyway, they have signed up to flying club. I'm wondering what the upgrade cost might be? The online price is £900 from Y to J. Does this mean W is full? What's the cheapest way to bag an upgrade? Is it at checkin?

Thanks for the advice in advance.