The ready-made StrongLink SL018 Mifare RFID reader module is a more cost-effective solution. It can be ordered online from StrongLink in Beijing, China, and you will have it in a matter of days.
I wrote a simple Arduino sketch for reading tag IDs. It also works with the smaller sized SL030, which runs at 3.3V. A complete Arduino library for reading and writing data sectors on Mifare cards is also available.
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