Well Mr. Mahmood , I have also tried at smart card application few months back and here is some tips / information for you

(1)Till now most popular type of smart card are secured flash/EEPROM type.
(2)They have some open/public area & some password protected.
(3) When card is first purchased or unprogrammed card password area is open to password writing/programming. This is done by system integrator (like you) or card service provider at the time of issue of card. After passowrd is written the password protected area can only be accesses(read , change, write etc) by first supplying password to card(EEPROM)(which has to be done by authorised access equip/appli/soft).
(4) These cards are available in capacity of 256 , 1k .. 16 kb.
(5) These type of cards & their readers are easily avaible. In India their typical prices for prototype model(small quanities are)
Reader(SerailRS-232 interface) - $30
Smart cards 256 / 1KB - $ 0.4 (in bulk they are cheaper)
(these uses ic from ATMEL and blank for printing you wn information)
(6) These cards are having simple 4 wire interface(+5V,0v, RX,TX) and you can program them and access them using simple RS-232 serial commands. (RX & TX are at +5v logic so you can directly inface them to microcontroller and for standard RS-232 voltage interface ICs are availble for ATMEL). STandard connector head for accessing these card is also which can be soldered on PCB.

You can get application details of these card from ATMEL web site.
These card comply to ISO 7816.
Second catagory is wireless version of these card for which you require a contactless reader(also available MIFARE brans in $60). These are slighly costly

Third catagory is microcontroller based but they are upcoming one abd are not easily availble .