Question

what are potential costs of corruption and bribes?

Answer 1

corruption and bribes increase cost without contributing to the product.

All bribes tend to be added back into the cost in some way
A bribe to get a contract usually results in a biased selection which ofter overlooks the most qualified or lower cost provider.
A bribe to pass inspection may result in unsound construction
Corruption can result in people not performing their duties but collecting monies
Corruption can result in theft of materials that increase associated costs like replacement of the materials and scheduling problems because what is needed is not on-hand.