Working as a sales agent

If the matter is as you describe, then this
work is permissible and there is nothing wrong with taking this commission in return for your efforts in finding customers.  

We will quote to you a fatwa of the Standing
Committee for Issuing Fatwas concerning a similar case: 

Question: 

I am the owner of a trade office and I work
as an agent and go-between for some foreign companies that manufacture permissible kinds of clothing and foods. These companies send samples of
what they manufacture, along with the price of each item, and I show these products to dealers in the marketplace. I sell them to them at the
price stated by the company, in return for a commission from the manufacturing company, according to my agreement with them on the rate of
commission. Is there any sin in that?

 The Committee replied:

 If the situation is as described, it is
permissible for you to take that commission and there is no sin on you.

Fataawa al-Lajnah
al-Daa’imah, 13/125.