I agree, outrageous.
I work for what might be considered a well established school. Here the headsets are a plenty, but they are all knackered.
After about 700hrs of instructing I did go out and buy my own pair as at my medical renewal hearing loss was discovered. The noise level in a C150/PA38 is way above any health and safety regulations.
If I was starting again, easy to say now, but I would buy active noise cancelling from the start. Tried some the other day, they really are great.
Finally, it is impossible to instruct effectively if you cannot communicate. Wait and see how you feel after 7 hrs of noise.