Worry about whether or not you like the job, and if the job is right for you first. Once you and the interviewer have convinced each other you're the best person for that job, then the topic of salary should come up. Otherwise you're either wasting both of your time talking about salary before you even know if you want (or will be offered) the job, and secondly, if you quote too high of a rate early on, they may not talk to you about the job in the first place. Better to convince them they can't live without you first, then they may be more willing to negotiate the salary you really deserve, even if it's on their higher end.