It is very simple to make and there is no way to justify the $38 tag. DIY production would be about $5 if you buy all the components, although most hobbyists will be able to bash it together for free from random bits they've found in the drawer. And it's cool because sending an IR signal is as simple as playing a prerecorded audio.

There are no risks to the phone that I can think of. The load the LEDs represent is about a quarter of a load presented by your average headset, so they won't damage your audio output. The LEDs do, however, require a bit higher voltage (even though less current) than the headphones. Which means there might be the risk of the phone not producing a high enough output to light them up. Does anyne know what the max audio power is? Anyway, if it turns out not enough then a boosted version would do the trick. And while we are playing with the boost, we can as well double the IR frequency with no changes to the phone, at the cost of using 4 LEDs instead of 2.

The input might be a challenge though. How I wish there was an external mic or line in on my phone!