Came across this on Twitter today:
The Ping))) is a top-selling product from Parallax.
Seems like a fair comparison. You will always find cheaper copies of anything, and the customer benefits with more choice. The message was pretty clear, like the argument for Levi vs Walmart jeans.
One observation he made (but didn't elaborate) was that if you run out of pins on your cheaper Arduino, you could buy a bigger Arduino. I suspect that could cost more than the sensor price difference, so that would be another valid reason to support the case for choosing the original PING module over the cheaper copy. ie. when your Arduino is running out of pins or processing power to handle the 2-pin protocol of the cheaper sensor.
HC-SR04 is made by many companies, so how about the variability among manufacturers? Suppose you designed it into a product; how could you guarantee conformity and consistency with a specification? The LaserPING is also a drop-in replacement for environments where ultrasonic does not work well, or a higher number of readings are required/second, etc. Interesting as well, our manufacturing costs are 2-3x higher than the retail price of the most expensive HC-SR04. We're using the highest-quality, most consistent transducer we could find.