Software as a service (SAAS) services featuring software for enabling Group Purchasing Organizations(GPOs), namely, associations, buying groups, cooperatives, and national franchises to: manage vendor rebate incentive/volume discount programs; to securely share and report business information online with member companies; to implement business-to-business (B2B) e-commerce data warehousing and electronic document exchange between GPO headquarters, member companies, preferred vendors, and strategic customers; and to deploy multi-vendor marketplaces and storefront websites, which facilitate online vendor program sales and member purchases