I would hire a DBA on the spot if they wanted to be generally useful in other roles too (i.e. did not insist that they only do databases).

Databases are such an important part of modern systems it makes sense to have an expert on them on board. I think that would pay off many time over.

However, I'm in a small team and I think it's important that everyone can also help out with a little bit of everything depending on what's going on.