Is the commission paid to obtain better-priced and higher-quality deals and contracts permissible or forbidden?

What you are doing — researching and negotiating for the best price with quality — is the core of your work as an agent. An agent must work for the benefit of their client. Therefore, you are not entitled to the commission offered by the supplier. Instead, it belongs to the manufacturer and the employer, because it is, in reality, a reduction in price, and you receive a salary for your work.