How do I pitch a salary number to a potential employer when I have few comparables?

How do I pitch a salary number to a potential employer when I have few comparables? I work in academia, but have been doing some consulting and contract work for another company. I've had a great relationship with this company for over a decade and have done many different kinds of jobs for them. They've always liked what I've done and I have always enjoyed working with them. The work I've been doing lately is AI-related, which is an area I have extensive experience in. For that reason and others, the company has been talking to me about a full-time offer, which would involve me leaving academia and joining them permanently. My question is about salary. The company has asked me to pitch them a number or a salary range. The place where the company is based is far more expensive to live in than where I'm currently located, and salaries in that field are much higher than in my academic field. That makes me think the range I name ought to be quite a bit higher than my current salary. But the position I would have is somewhat of a boutique position, custom to that company and the work they do, and so I've had a very hard time finding comparable jobs and/or salary numbers against which I can norm my education level and experience in order to know what to pitch them. I am looking for any opinions about this salary situation, or how to think about numbers when there are few exact comparisons.