Kolkata Airport Lounge | Breakfast and Lunch Buffet | Complimentary access with credit/debit cards 

It is around ₹1,200 if you pay for it. Honestly not worth paying that much for the kind of service you get. Most people gets access through select credit/debit cards by paying only ₹2 as card verification charge.

Card/cash etc. It's better to get access with rupees 2 only. Check with your bank if airport lounge facility is available.