If you know what you're doing as a customs broker then doing the customs brokerage yourself would save you money and be a good idea.
Although if you hire a customs broker you also save time although it might cost you some money but if I had to do other things I would personally rather hire a customs broker to do the job.
Then that would free up my time and save me the headache of having to deal with the issues of the customs brokerage.
But if you want to do it yourself you'll save some money but it also takes time to do the customs brokerage.
Even if I knew how to do the job of customs brokerage I would still hire it out and use my time for something else.