Grades and finishes drive cost
300-series alloys dominate food, beverage and pharmaceutical work; 400-series shows up where hardness matters more than corrosion performance. Finish specification — mill finish, brushed, #4, mirror, electropolished — often affects labor cost more than the base material choice.
Sanitary and food-contact work
If the assembly contacts product, discuss weld profile, crevice-free design, drainability and cleanability early. Shops that regularly build sanitary equipment will raise these before you do; shops that do not may quote low and then struggle at inspection.