Goofballtech:
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.
Not only that, but in order to effectively build such a circuit, you need to have access to a 2-channel oscilloscope to compare the output ping to the received ping. Given the numbers of the parts, these devices likely have a 40 KHz resonant frequency (you might want to verify this, I am only guessing).
The following circuit is a homebrew system using similar devices (albeit @ 24 KHz - so you would need to compensate for this difference, likely):
http://www.kerrywong.com/2011/01/22/a-sensitive-diy-ultrasonic-range-sensor/
Note the use of the oscilloscope...
Also - if the devices you have can be used as both a transmitter and a receiver (that is - the parts aren't differentiated into "transmitter" and "receiver" parts), then you might be able to get away with a single element system, using circuits similar to these app notes:
You'll want the circuit for the "AT90S2313" microcontroller; this is a small Atmel microcontroller (http://www.atmel.com/Images/doc0839.PDF), but you could probably easily do the same thing with an Arduino.
Of course, no code is provided with this app note (you might be able to get something from Hexamite if you asked), but the idea is to basically output a pulse (on pin 14/PB2 of the AT90S2313 in the note), wait a short bit (to allow the circuit to settle), then listen to the input (in the app note, on pin 12/PB0 of the AT90S2313) for the return echo; the difference in time of course relating to the distance.
Note the "weird" back-to-back diodes in the circuit; these may appear to be "wrong", but I assure you they are very "right" - they essentially act as a voltage clamp to keep large spikes out of the system. They are necessary.
Of course, given all of the above, you would definitely need and want an oscilloscope for the project. In the end, you haven't saved yourself any money, but instead have opened up a huge learning opportunity, should you choose to pursue it...