Suppliers of electrical installation materials

We have succeeded in securing larger government contracts and are currently looking for a reliable supplier of electrical installation materials at reasonable prices. If the partnership works out, we intend to collaborate on a long-term basis and will have no reason to approach other suppliers! A key condition is that payment terms must be a maximum of 60 days. Our contract stipulates invoicing every 30 days with a 30-day payment term.
Upon request, I will first send you the bill of quantities for the first, smaller contract worth 9.6 million.
We have a second confirmed contract worth 20 million, and a third worth 145 million.
Location: Not important. What is important is that materials are always delivered on time.
Deadline: As soon as possible
Additional information: The prices you quote for each contract must be adhered to throughout the entire construction period. They cannot be increased, as these are government contracts.
Should the supplier of electrical installation materials require a contract for works, we will be happy to provide one.