JotForm Prefilled Stocktake Development

Seeking a price for an advanced JotForm developer to design a Jotform which allows a site to stocktake its consumable inventory each month. The form would allow the user to select the site. Each site would have a pre-filled quantity of each item of inventory which they should hold (varies from site to site). The difference is then submitted as the requisition for resupply. Already have a JotForm which was built previously - but relies on a complicated and unstable set of excel spreadsheets.