Is it permissible to add a sum of money to the prices of materials purchased with the private funds of the purchasing committee, knowing that the department does not disburse the amount until after inspecting the material?

The agent is trustworthy, so he is not liable unless he transgresses or is negligent. He is not permitted to add prices to the materials he is entrusted to purchase, as this constitutes a breach of trust. The alternative is for the administration to allocate sufficient funds to him, or to purchase the materials from him through a non-binding Murabaha promise.