What is the ruling on paying a commission or percentage to a contractor who works for the plot owner, so that he deals with my products?

The agent is entrusted [with a responsibility] and must seek what is best for his client, not for the one who gives him a commission. Giving a gift to the contractor-agent corrupts integrity. However, if the situation of people has deteriorated, and contractors no longer deal except with those who give them [something], then there is no harm at that point in giving the contractor what he requests, in order to obtain a permissible benefit for which there is a need. The jurists have permitted spending money to rent a stud for breeding when there is a need, and they likened it to bribing an oppressor to avert his oppression.