More than 10 yrs ago, I learnt my ropes arranging school / coporate anthems etc. This guy basically deals with the client, gives the job to me. I have to arrange, programme MIDI, play, record, mix and give the finished product to him for presentation to the client. Normally there would be 2-3 amendments. I get paid less than 10% for each job and that guy gets the 90% (granted, he writes the song).
A few years later when I decided to move on to other things he didn't manage to stay in this business for long. Why? Because he couldn't find someone else who can give him the quality for that price.
The moral of the story is, the only way to evolve from your current situation (besides Plan A, the aforementioned become a scumbag and cut off the middle-woman thingy, which on its own requires another set of skills and investments in time, effort and $ in wining and dining with people all the time) is to be the best in what you do. In fact be so
scary good, and establish an reputation amongst the middlewoman's clients, such that her future clients would expect such a standard from "her".
That's when the power shifts from her to you. She won't be able to get clients if she can't find people who can deliver the quality you deliver, regardless the cost. She will die a natural death, unless YOU agree to continue working with her, of course at a price that you fancy
In fact you will start seeing other agents wanting to represent you at a much fairer price.
But if you are just marginally good in what you do and can't create extraordinary value or USP in your work, then you are forever condemned to be a "peasant". Just like those poor coffee farmers who are forced to sell their cherries dirt cheap to the big corporations with huge bargaining power and access to many regions. But if only the farmers acquired the knowledge and capability to improve their crop quality and yield, and process their coffee cherries, it would fetch a far better price.
Now in what I do, I tell people who try to negotiate rates with me: "If you want a tailor, go to a tailor. You will have no problems getting "that look" you want at a far lower price. I'm a fashion designer."
Or at least in my dreams
