I agree, having a good local shop is ideal, but we hear so many stories of bad local shops.
So what makes a shop bad?
1. One reason, obviously, is
intentional bad advice. That is when, for instance, a shop has identified specific items to push because they give the highest markup. The employees are ordered to work hard to direct customers to those items, even though the item on the wall next to it might be a better choice for the diver. When the first shop I worked for switched agencies, the owner of the agency suggested this, justifying it on the grounds that the higher markup equipment was good, so it wouldn't harm the diver to use it.
2. A second reason is
limited supply. A shop will sell you what they carry. When it comes to carrying things, they have to be selective. They usually have contracts with suppliers requiring certain amount of annual purchases of their line, so too many suppliers will make it too hard for them to meet all the quotas. A few years ago, I met someone at a shop I didn't know, and because he was late, I wandered around the shop aimlessly for a while. I decided that the shop had pretty much nothing I would buy.
3. A third reason is
limited knowledge. In many cases, the people working the retail floor have a very limited knowledge of diving, especially advanced diving. These are often minimum wage people with limited experience. They will push customers in the directions they know, and what they know may be filled with myths. Years ago I ordered steel tanks through the shop for which I was teaching. When they came in, the employee working the retail floor helped me take them out of their boxes. What kind of tanks are these, he asked me. Why do they have round bottoms? He had never seen a steel tank in his life, and he did not even know they existed. I am not mocking him. I was an instructor who had never seen a steel tank either until I started tech diving training.
If you are going to frequent a local shop--and I believe you should if possible--make sure it carries a diverse inventory and has knowledgeable staff. A shop that offers instruction in technical diving is a good sign. If you walk in and see mannequins dressed in gear packages of different levels of quality at different price points, head for the door--that is one of the techniques recommended in #1 to steer you to specific items. ("Well, yes, this beginner package is safe, but if you are under water, don't you want the best?" Are you going to go cheap on safety for you and your family?")