IMHO, hiring a junior DBA from the outside isn't going to cut it. You actually need to stop working and start teaching. You have 20 developers to chose from. From those that you think have the right attitude, take 2 of them under your arm and teach them things they need to do query tuning, handle 90% of the questions the Devs are asking you, get 1 or 2 of them up to speed on SSIS, etc. Have them start doing code reviews with you moderating the review. Teach both sides. It'll be a bit tough to do at first but it'll pay off huge down the line. Then, split the group of 20 developers in 2 and assign each group to one of the two people you trained with the single instruction to "pass it forward".

Published standards and a wiki on how to do things will help a whole lot, as well.

The bottom line is internal training and you're the key to it. I teach at every shop I work for and it pays off in spades for everyone involved.