The chip can vary drastically in price, I work for a company that makes and sells chip cards, contact and contactless, which is based in the UK.

One of the simplest chip card is a simple I2C eeprom, based on a 14c02 chip, same interface as a 24c02 but with no address select lines. The more expensive types have extra logic to control the access to the data they hold.

It all comes down to how secure your applications data storage needs to be and how much you are willing to spend on each card.

Steve Troup