I charge 6% no vat. But I am very niche and run from home, its rare for me to achieve the 6%, its usually discounted for some reason, such as I have a buyer waiting, or we have a huge haggle and I discount my fee to get it over the line.
8% plus VAT is the norm sometimes with a fixed lower amount for lower value boats. Some small brokers charge lower and may not be registered for VAT. I paid a flat 5% to a small independent broker.
The key thing with brokers is the ability to get the highest net price for you, but this is often difficult to determine in advance. A broker close to the boat is usually and advantage for viewings, but you also need to look at their on line listings as this is the main advertising medium now.
A friend of mine has given upon the online brokers & is now going with a local well known bona fide broker
Charge is 8% & includes some time "on hard" storage for free. I think she said it was 6 months, but I would have to confirm. The fee is £1000 so that tells one the value of the boat. My friend did not mention VAT so I cannot comment re that.
Almost all brokers, even if they have bricks and mortar premises use the on line listings - Yachtworld Yachtmarket and Apolloduck. The days of needing to be in a boatyard or marina to attract enquiries have gone, although it is of great value for viewings, particularly if you are in somewhere like Hamble where there are large numbers off boats on display or located in the marinas. in other less concentrated places it is less useful.
As I suggested the real value of the broker is finding the best buyer and turning the interest into a clean sale. That does not need an office!
I chose my broker due to an issue I had when I first bought my boat. I needed a photograph of the engine serial number - can't remember why - and the boat was 600km away. I sent a cheeky e-mail to a broker at the marina where my boat was moored asking them if they could do me a great favour and collect the key from the marina reception and photograph the engine serial number for me, and send the photo by e-mail.
I got a very friendly reply with an attached photo of the engine serial number the same day. 11 years later I sold my boat using the same broker.
I have no idea what fee he charged the buyer - it sold within 2 weeks, but he did say he had a list of waiting customers.
I didn't pay the broker any money and I got what I wanted for the boat, so I was very happy. This included a load of hassle due to my UK registration and the Slovenian and Croatian authorities refusal to accept it was VAT paid. He sorted that out so he definitely earned his commission.
I would only sell a boat without a broker if I lived very near, there were no foreign languages involved, and I had the time to do viewings, sail trials etc.
The sales contract was signed in his office at the marina and while I agree an office is not absolutely necessary, it was handy to have the brokers office 150m from my boat.