I agree that it sucks! However, I used to have business and personal connections with one dealer for the Mazda Motor Corp (USA)spare parts business - and their pricing matrix reached 400% markup in some areas. I now work for a custom machine manufacturer where we build $80k to $200k machines customized to run different products and it is a standard practice for us to mark up components that we buy off the shelf to help cover the costs associated with the storage space, design/integration time, heating, shipping personnel and equipment, etc. etc - and to make a little money in the process. This is not to mention parts that we design and manufacture ourselves. Basically it costs money to do business/move and store parts regardless of where it originated. We also guarantee a degree of quality and knowledge about how that part should be used that you may not get if you buy, or have manufactured, something somewhere else - and that's probably a fair statement of Hobie, Nacra, etc.
300% markup? Maybe that's not reasonable considering an off the rack 8 foot piece of 1 inch extruded aluminum tiller connector but as the rules of supply and demand apply, someone will most certainly take advantage of the disparagy and profit somewhere in the middle. However, that's not to say anything about 'class' rules apply.