Can anyone build an economical and small device as described below?

The device must receive 'instructions' from any 'point of sale' (POS).
The POS is basically a register that you can find in any store when you buy something.
The 'Instructions' are usually receipts generated by the POS system.
The device must be able to connect to any POS using any connector such as USB, etc.
The device must hold those instructions temporarily. Let's say for 30 seconds once they are sent to the device.
The device then transmits those instructions to the iOS app. For that, it must be able to connect with the iOS app wirelessly through NFC or Bluetooth.