No matter what the Customs officer said there is no requirement to use a broker clearing goods you own. Just like going to court, you can represent yourself, although it's not always a good idea. Using the same example lawyers can charge a lot or a little, no rules on the rate.
Brokers fees vary according to the market, major port of entry plenty of brokers to chose from competition keeps the price down. Interior entry port few brokers you may pay more. Working for international company's 40 plus years I have entered hundreds of shipments myself. However when we had volume repeat shipments same commodity or complicated entry's always used a broker, shopping the price.
Last firearm I brought in the country on our own ship, no freight charges, consigned to a FFL importer licensed dealer. made the port entry in bond to his Colorado shop myself and shipped in bond by common carrier, arriving at his local bonded warehouse he entered the gun at his local Customs office. It's better in my opinion to consign to a dealer who can in the case of a modern gun mark it with his importers name, or not if it qualifies as antique.
Local customs officer knew him and had entered many guns for him, no issues.
If you are paying brokers too much shop around.
Boats