The central locking/remote locking systems are available for about 4,200INR. I think brands like Autocop/Xenos offer this with impact sensors at this price. The kit would include all the necessary equipments for central locking as well. In case the the car has central locking, only the remote locking equipments are used.
In case you are interested in power windows (i.e, if yours doesn't have one), you could get one for about 10,000INR. I had installed both the power windows and the central/remote locking systems for my LDI. The link to the installation report with pics is here:
http://www.team-bhp.com/forum/test-d...io-1-2-nv.html (Family battle: Swift 1.3D v/s Palio 1.2 NV)