Bellwether Purchasing Software Reveal the savings Bellwether Purchasing Software can provide your organization. Enter the data into this calculator and see how quickly you can realize the payback of your investment with Bellwether Purchase Order Software. Bellwether Purchasing Software solutions offer individual modules or you can purchase the entire suite. Available modules include: Purchasing Requisitions RFQ Receiving Inventory & Warehouse Management Asset Management Invoice Approval/Reconciliation