Saving money is relative. You saved some buying in raw but it's going to cost you in time to figure out how to do the things that are done for you with a more expensive breakout form of the sensor.
To save money, I bought a two-piece ultrasonic sensor (which was not designed for Arduino). It does look similar to other ultrasonic sensors. I have looked around and I can't find an informative data sheet or a tutorial. I don't even know which side is negative! The codes on the sides are: UST-40T, 400SR 04 62. Please help!