Batch NFC card encoding

I hope to start a project that will require me to encode 50 - 300 NFC cards for each person, and there may (in time) be 100+ users.

I have just looked at commercial encoders, and they average 6p extra per encoding, plus 24p per card, plus £10-£20 set up fee ... Each time. Or you can pay $10 a month for 100 cards, or around $100pm for a max of 1,000 cards. Expensive

I'd already researched building a reader, (rather than relying on a phone as the requirements were minimal) and found cards on AliExpress for NFC reader using I2C, a micro SD card on MOSI, realtime clock and ATMega board. (Total cost$10) So wondering if I can switch that around to be a writer.

Here's what I propose, so add comments if viable.

I have already written PERL code that will create a sheet of unique barcodes. I plan to stick these to the blank cards. The idea is to place the card on the reader, and scan the barcode with a handheld unit. The sketch will read the barcode (nothing more than a three letter code) and encode that into the card. That should make the process quite quick and easy

I know you can get libraries for the cards; would it be simple to integrate the scanner too? (In PERL, that comes in as if someone had typed something on the keyboard)

For the opposite side of the coin - rather than building the above unit -I'm now looking into a unit you can plug into USB of phone, and perhaps using TASKER to read it. (All I want to do once read is to record the three letters into a file, together with a time-date stamp)

If you are talking to your arduino board through the Serial port, you either have to have the Serial Monitor in the IDE open and "scan in" the barcodes there and send them or write some custom software (in perl?) to open the COM port and communicate with the arduino board.