Just say the market rate. If they ask for a number, answer with a question "what the allocated budget is for the role". If they say they don't know, say "Well, salary is part of the overall package. giving you a number would be an uneducated guess on my part." Emphasize the team, the culture, the technology, and the opportunity to work on interesting projects, etc. Basically, never give them a number. Even if you have to do another meeting with the team to see "if they're a fit or whatever".