How to ask a friend for a market rate offer?

I have a talented designer friend, and I want to hire them for a landing page for my project. I don’t want them to do me a favor, I want to pay the market rate.

How should I communicate I’m expecting them to give me a market-rate offer without being weird?

(I would still accept it if the offer would be high. I just want to know they are happy to work on the project.)