Application Needs Built

I have laid out the product blueprints for a piece of software I need built. The product will be used as a portable kiosk inside grocery stores and other retail locations, and needs to be compatible with tablet devices. It will probably be easiest to have built as a website that is formatted for mobile devices. The site will have a very intricate filter system, needs to be able to keep up to the date moment with inventory in stores (connected to the stores individual POS system), and be able to have very easy manual system entry remotely. I can only give limited information without an NDA signed, so I am looking for reasonable bids on a build out of a site that will need a moderate backend system build out that will be heavy on databases, linking in different POS systems, and is easily accessible via different mobile tablet platforms. The filter system will be intricate, but is the main part of the application and shouldn't be rocket science to code. I will need a front end userface designed also to round out the final prototype.