Custom Build an App

I would like to make an app on my iPad (does not have to be posted to the App Store) for my consignment sale. What we would do is when the people sign up to consign, I will make a QR Code and send it to the consignor. When they come to check in, we would scan the QR Code and something would pop up with their information and say is it correct. If it is, then they move on and sign on the iPad to our terms and agreements and their signature and information goes on to an excel spreadsheet. I know a lot about electronics and can even do some of the work if needed. Thanks!