How to reduce the cost of developing such a terminal?

Question

Arduino

Hello!
There is an idea to make small terminals for receiving payments (hryvnia, denominations - 1,2,5,10,20,50,100,200 and 500).
Must be placed on the wall.
You need a small color screen (at least 10 "), not necessarily a sensor. You
must have wireless adapters (regular 2g or 3g), i.e. Internet via a SIM card. Although you can also consider the option with an rj-45 port, but such a network there is not at all points...
The task is the following - the user chooses what to pay for, deposits money, payment information goes to the server.Also, when the terminal is turned on, some service information will be requested.. therefore there are no special requirements for the Internet.Well, maybe also (at the debug stage) once every 3 hours the terminal will reset its screen so that software glitches can be detected))
At the moment, I have looked at this option in order to take an arduino, connect a TFT display to it, a separate 3g module, and a separate bill acceptor. And order the case from ordinary iron, which will be tinted.
It turns out about 300 bucks for the device ... Tell me someone, how can I make it cheaper?
P.s. validation of banknotes is not needed, only the definition of the denomination is needed ... an ordinary plastic box is suitable as a money cassette. No checks, keyboards, cameras, etc. not required

Answer 1

How to reduce the cost of developing such a terminal?

Take it ready.
Google it.