I would simply ask around the maritime industry in your area. One or two names will keep coming up, and you can be fairly sure that those will be the ones with good reputations as knowledgeable brokers who are easy to work with.
Specifically, you're looking for a "buyer's broker". They will represent you throughout the process and they split the commission on the boat
you buy with the selling broker
so there is no cost to you.
That said, no buyer's broker wants to be saddled with having to educate a client from scratch and show them 50 boats. You and your spouse need to educate yourself so that you're prepared with your own list of requirements, can answer questions confidently, and are in a position to evaluate what you're being shown.
There are lots of liveaboards on this forum, and even more who have extensive familiarity with a broad range of boats. You'd do well to read some of the prior threads on the very same topic and ask additional questions here.
Ideally, you and your broker will zero in a few makes/models of boats that fit your requirements. Then the real work begins. The broker will pull up listings for those boats, and should have the knowledge to parse out the relative strengths, weaknesses, and value of each one to help you select which ones you go look at.
Every boat, even of the same model, is different, with different levels of maintenance
, condition, etc. Layouts and equipment
change from year to year. You'll find boats that are in dramatically better condition, and a better value, than sister boats 5-10 years newer, so you'll need to be prepared to evaluate what you see and what it means for your plans for the boat.