Hi Akash budget is not really a show stopper here...I am willing to spend around 30K or so to get some good stuff for Navigation+Bluetooth+reverse camera support.
I checked on the mapmyindia website, & the best they have is Zx150 Deluxe & is worth 19,500 INR, or 21,240 INR with a 2yr map upgrade plan. Looks like it has all the feature's I need. It also comes with a free reverse camera as of now. And additionally it comes with a aux connection to your audio system, so you can listen all those songs on the 8GB of the SD card in it on your car audio. I just checked & the Dzire integrated audio has a AUX in right on the front.