AyushChand:
I am looking for a ping sensor alternative coz its 30$! Has any one tried the HC SR04 in ebay sold from China for 2.5$? Is it good at all?
I have a bunch of these sensors and they all work just fine. My NewPing library accommodates for the different styles of sensors out there so they all work the most effectively. Buy 3 of these sensors from 3 different vendors on eBay just to be sure. I did get a couple that don't like to work beyond about 100cm.
Tim