What is your best answer to employer asking you about your expected salary in job interview?

First thanks for asking, normally the headhunter and/ or the new employer knows your salary with all benefits, so if they find you suitable for their requirements and within the budget they will starting negotiations with you, at this point, the new salary expectations depends on your interaction with the employer and your image imprinted into your employer's perspective of you, thus this differs from one person to another depending on your ability to impress your employer. If you are aiming high mainly applying to a big and famous company, preferably if you check their salary scales before aiming high in order to have a solid negotiation base.