My $0.02 is that many brokers and some good ones are reluctant to spend a great deal of time with prospective buyers that are "looking" to purchase... but aren't sure exactly what they are looking for. It's another story if you can cite 1-2 specific builders, models, size, price range, etc. that you are considering / prefer.
I've had good luck once I decided what I wanted and had a listing I thought I would be interested in. I / we did a lot of looking, talking, "kicking" tires before that point.
If you are unsure of the specifics - there's a lot of great info / tips to get started in the
Boat Search 101 thread.