A common mistake in projects is choosing the cheapest supplier to save on costs. There is a risk that it will be because it cannot compete on quality with other suppliers and will have to compete on price. The other solution providers are probably better at managing uncertainties, and choosing this one adds uncertainties and delays to the project.
A 20% discount in the choice of the supplier can represent only 2% in the total cost of the project. Is it worth putting at risk the delivery of the entire project, the costs due to delays, or the extra costs due to quality or errors for a supposed 2% savings?
Read in the book “Critical Chain” by Eliyahu M. Goldratt.