Thanks for your post project.
I read your description and very interested, clear to it.
Barcode & QR code scanning is my major.
I have developed many apps that by using scanning barcode & qrcode(upc-a, upc-e) ordering and buying products before.
Barcode & Qrcode scanning is based on zbar, zxing.
I can provide you good result with good result.
If you want, I can show my projects with screenshots or team view.
Please ping me to discuss more detail about your project.
Thanks