I wouldn't even consider "having one", any idiot that wants one could go eBay and get the same type of garbage for less. And it would be worth every penny, as long as it's under $20. As I said all it can do is add to the perception of more power by intercepting and changing the signal between the throttle and ECU to richen up the fuel curve or make the T/B open more quickly.
$300, the jokes on you.