The general rule in salary (and other money-based) negotiations is that “the one who says the first number, loses.”
Instead of offering an insipid and totally meaningless “it’s negotiable” (The question is the first round of negotiation, and by asking it they have started to say “Let’s negotiate your likely salary.” You don’t answer that opening round of negotiation with “it’s negotiable”, since the negotiation has already begun!), answer from a point of demonstrating your knowledge of the position, the salary range offered for the job and why you are perhaps worth more than some other rube who would start at the lowest possible salary.
For example, you can express – honestly and confidently! – that you have daily access to a worldly, diverse and highly educated and experienced network of professionals, business owners, retirees, librarians and current and former scholars and academics who have assisted you, and will continue to happily assist you, in all manner of business and personal issues. (Just don’t say the word “Fluther”, as it will sound strange in their ears.)
You might also mention, “oh, for instance …” the types of advice that you have offered in the past that you’re particularly proud of, and which demonstrate the high degree of readiness you bring to the job at hand. (It’s on your “Best Answers” list.)
And so forth.
You should acknowledge that you are aware of the current salary range for the position, and that you feel qualified and deserving of a less-than-minimum offer, because … and that’s an essay question that you have to answer.
Consider that if you’re talking salary, then they’re pretty sure that they want to dance with you, but they want to know if you expect to be picked up in a limousine driven by a liveried chauffeur, or will it be satisfactory (and do you have realistic expectations) of being picked up in a nondescript four-door sedan driven by the owner. (This is the point where you remark – figuratively! – that you expect that the sedan shall have been recently washed and vacuumed – detailing would be nice! – and that the driver should pick you up promptly, and at the door as a young woman of your quality and bearing deserves.)
By all means ask for a salary that’s higher than you ‘expect’, and be prepared to accept what you deserve. Just don’t settle for less. They won’t throw you out of the office if you ask for a high-reasonable salary. Part of the negotiation process is to see how you handle yourself. Make us proud.