In general dealers can sell at whatever price they wish to do so and manufacturers cannot fix prices. However, with most suppliers, there will be a contractual agreement about what prices the dealer is allowed to advertise. It is in the dealer's interest to maintain margin and on higher quality, specialist products that are only available by walking into a bricks and mortar shop with proper service, there is far less need to offer big discounts. This is certainly the case with a brand like Naim and it is one of the reasons why they hold their value so well on the second hand market.
It is the same with cars. When companies like Citroen offer huge discounts off list prices the residual value of their cars is relatively low, but VWs offer better residuals, partly because of quality/longevity and partly because there just isn't the same discounting culture when the cars are new.
All swings and roundabouts in the end.