It is not realistic to say that you have made a choice from a place where there is no variety. It is also not fair on the part of the store owners to deny you variety of a product that is known to have a wide range. It is best that you let clients make their own choices of what they feel is best for them. There is a store that does exactly that. They have a wide selection of products.
You will find a wide selection of car stereos so that you will be able to see what is most ideal for your car. We are unique and so are our preferences. What you would need is not what the other would prefer. So, it is good that you insist on the wide selection so that you are able to see just what you want.
The others that you do not need will also be displayed for you. Sometimes you make choices or you develop preferences because you do not know there is an alternative. But, when you see others, you can even change your mind because you would realize that there are other better options.
An example is when you believe that Sony car audio systems are the best because you never knew about the others. When you get to shop online, you would see Kenwood, Alpine and even Pioneer models and you change your mind. So, insist on a wide selection.