I bet you know within 5k what your target salary is? Are you afraid that you may tell them your top price and you won't know if you missed out on 2 or 3k?
Or do you think you'll scare them off?
I like the unofficial approach, I do it quite often. I have my salary tables and they are what they are and i quite like being open about that.
I would always hire someone with a view; I always have room at the top end of the grade so if they step right up, i'm not holding them back on their true value later on.
IF they are good enough to be at the top of the grade, I'll bump the grade to the next level and give it a 'stretch' or at-risk element.
Be honest, realistic and tell them what you really think you're worth. Then be happy with the respsonse.