They can shop elsewhere..anyone can always can buy something for less if they spend enough time and effort to do so..I do not consider $50 difference to be the deciding factor, some may. In NY area fees are close at every shop. All within a $50 to $100 range of difference. We are not the cheapest nor are we the most expensive in the area.
So just to get some clarity and perhaps finality on the issue, let's say someone comes to you for OW certification.
1. They did the PADI eLearning
2. They have a mask, snorkel and fins.
3. They will not buy any gear.
4. Classroom, pool & OW dives.
What will you charge them to get certified?