As another poster said, I think the approx. regular cost to keep a bird overnight is about $45 or so, as that is also about the price one of the local A.V.s charges here (I think it was actually $35 here - if my memory serves me correctly). Now if a vet tech. has to truly stay at the bird's side around the clock or after hrs., then of course that is a different story but I don't think that is the case here?
Usually there are other birds/animals in the office that also need tending to overnight/during off hrs., therefore the vet would not have to pay qualified people to tend to just Buddy. Doesn't hurt to ask anyway.