Here is my example to my preamp. To develop my preamp it cost me over 5,000 in various parts just to try them out to see how the preamp would sound. Along the way there were so many changes based upon parts availability and how they worked together. I had read up on resistors, capacitors, wire, etc., to use that so many others found to be better than the other ones someone else liked. I had to hear most of them myself to come up with what worked for me. Then there was the chassis. So far that will be the biggest expense in the entire design even with custom wound transformers made to my specifications. So for example, if the preamp comes in at actual parts costs around $2500 how much of a market up should I charge. That does not take into consideration cost of parts to get me there, over a year or two of time to develop the component, chassis designs, etc. Plus the cost to use a copper chassis which I wanted to use would add another $500 minimum to the cost of the chassis. Try and find companies to make a chassis or cabinet for you and then you can see what it takes to manufacturer a product. I have not even mentioned website, custom shipping box, marketing expenses, etc. It all adds up very quickly. Until you try to manufacturer a product yourself, you cannot really know the total expense.