There are three variables when considering price: trim level, paint, and geography.
Tata Nano Standard: three color options, single-color seats, and fold-down rear seat. Starts at $2,217 after fees.
Tata Nano CX: five color options, heating/air-conditioning, two-tone seats, parcel shelf, assisted brakes, fold-down rear seat with nap rest. Starts at $2,744
Tata Nano LX: all the features of the CX plus fabric seats, central locking, front power windows, body-colored exteriors, fog lamps, trip meter, cup holder, mobile charger point, rear spoiler. Starts at $3,347
The three options are the basic paint on the Nano Standard and either "Solid" or "Metallic" paint on the CX (the LX is only available with metallic paint). As you'd expect, solid paint costs less than metallic paint. We're guessing they just cover the standard with house paint.
Based on the pricing sheet we have, there are three regions: Nagar, Delhi, and Mumbai. A Tata NanoLX with metallic paint (BS3) costs $3,350 in Nagar, $3,388 in Delhi, and a whopping $3,642.
Thanks for the tip Otto!