You may want to look at business software that is already designed like quickbooks and peachtree. You can look up free software, although your risking your business to an unknown programmer that may or may not have gotten the program right. Many business software have different levels of software, from small business to multi-networked high level software. If you already know how to program Excel and need basic business formulas, I would recommend searching for business formulas with the specific task. Percentage markup is a basic business formula that can be found and inventory is an easy listing using the spreadsheet or database. The big downfall of inventory up keep is keeping track and using the same inventory numbers. (I worked for a office supply business that used a computer and did not have a grasp of inventory control. The number tracking became random and the inventory grew with random numbers being constantly assigned to the products. One way to get around this is barcode with a scanner, there are plenty of software/inventory suppliers out there that use barcode and scanners. RJF