Is money earned from brokering the establishment of information networks, by requesting price quotes from others and setting a profit margin for technical supervision, lawful money?

In this scenario, the questioner is considered a joint contractor, and it is permissible for him to accept the work and assign its execution to someone else for a lower price, so that he can take the difference, provided that he adheres to the employer's conditions regarding the quality of the work, and that the employer has not stipulated that he perform the work himself.