Design & Construction
Fixed Fee (Flat Fee) - Project scope is identified. Included is a sum reflecting work to be performed.
Time and Materials (T&M) - Based on hours spent and materials used.
Percentage Fee - A specific percentage of project/construction costs.
Per Square Foot - A specific rate times project square footage.

Purchasing
Cost Plus - Purchase of products, materials, fabrication, furnishings and related services based on item cost plus a specific percentage to cover handling, etc.
 
Retail - Purchase of products, materials, fabrication, furnishings and related services based retail rates to cover design services and purchasing.

Retainer
Retainers are typical for project commencement. Retainer fees vary, depending on project scope, and are applied to the overall balance upon project completion.