KD8NPB
Contributor
Do you really need to "practice" nitrox?
We do $4 air fills.
$5 air fills? That's crazy. It costs more than that to run and maintain a compressor. Air fills out here are $10 - $15. Of course little to no competition helps keep the prices up. Blending Nitrox takes more time, effort, equipment and potentially risk. $18 might be on the high side but not by much.
I don't think Nitrox certification is useless but you are correct that it is not as common as air and it costs more. You have to decide if your dive plans justify the extra cost or not.
We do $4 air fills.