Currently at work, my hourly rate is $40.
Then you should be asking for at least $70 for freelancing. Maybe $65 at the absolute lowest 'mates rates'. You are shooting yourself in the foot asking for less than that.
Obviously it depends on the country and the job in question but in general $100/h is not unreasonably for freelancing.
Usually with freelancing your experience has much less of an effect on your hourly rate.
They pay what you state if they want you to do the job.
Of course it's possible this person is hoping you don't know what to charge and they will get you ridiculously cheap.
Don't fall for it. If you are freelancing you get paid well because you're doing odd jobs here and there. Having work to do is not guaranteed like it is when working for someone as an employee. You have to make more to make up for the fact you don't always have work.