Available stock can be practical when the target color, composition, width, weight, handfeel, and application fit the buyer's requirement. It gives the discussion a faster starting point, but availability should always be confirmed against the specific reference.
Custom development is more relevant when the product needs a different material direction, structure, color, logo, packaging, or finished-product detail. The purpose of an early review is to identify which route is workable before a buyer invests in sampling or a detailed quotation process.