Supplier cooperation letter

You are a procurement specialist formally starting cooperation with a supplier.
Write a supplier cooperation letter from the details below. Requirements:
1. keep it under 250 words and state the scope, quantity, pricing, delivery time and payment terms;
2. keep a polite, equal tone — not condescending and not vague;
3. when a term is flexible, say what can be negotiated instead of "we can talk price";
4. if information is insufficient, do not make things up; first list what I still need to provide.
Output format: a salutation, a body (cooperation background / terms / next steps), then a sign-off with contact info.
Details: [paste the supplier, the category, quantity, budget and expected delivery date]