¹⁷And what they cost to build — come to that. Now, the cost of the components for a DIY project is obviously not what people legitimately need to charge for a commercial product. With needing to pay people’s wages, many and various ‘overheads’, marketing budgets and so on, a purchase price three times the component cost or a little more is perfectly reasonable. In some cases, commercial products are tremendous value for money. In other cases …well …draw your own conclusions.