What is the ruling on brokering a commercial deal if it becomes apparent that the buyer will pay a bribe to a governmental body, knowing that the broker refuses to deal in bribes and is suffering from financial hardship?

If your company's role was limited to mediation and you were unaware of the pre-arranged agreement, then there is no blame upon you.

As for deals that require the payment of bribes: If the bribe is to repel injustice or to obtain a right, then it is permissible, and the sin falls upon the recipient (the one who takes the bribe) not the giver. So, if your company is more deserving of the mediation (better or more suitable goods), there is no harm in paying this money, and the sin is upon the recipient. However, if your company is not more deserving of the mediation (similar or inferior goods), then it is not permissible to pay this money, and the sin falls upon both you and the recipient.