WOW ... What an interesting thread. Let me first say this : Someone asked why anyone would want to buy DIY cables ? My own DIY cables sound better than ANY of the big manufacturer's cables do. How do I know this ? After owning a high end audio store for several years, I have heard and owned ALL of the best cables at VERY expensive prices. I have been able to compare my cables head to head with the best from Tara, JPS, Crystal, Kimber, Synergistic, Nordost, etc, etc .... When a DIY'er becomes obsessed with experimenting for over 20 years building his own cables, he will learn what does, and does not work ... what different spacing, conductor size, conductor type, conductor count, construction technique, dielectric, etc does, and how best to optimize it. Since I do not sell my cables to people who will be constantly plugging and unplugging the cables, I do not have to use extremely strong, dynamics robbing outer jackets on my cables, which means my cables sound vastly more open, transparent, and dynamic. And this is only one example.
So the answer is : Many DIY designs smoke what the manufacturer's offer.
But if I were to sell my cables at a profit, I would have to figure in the cost of conductor material, heat shrink, terminations, outer jacket material, cryo costs if applicable, silver solder, contact enhancers ( Furutech Nanofluid is damned expensive ), etc .... For my interconnects for example ... I also have to figure in the cost of the special Techflex I use that retains a set shape while bending, and the cost of the professional seamstress who sews my channels for my conductor spacing in to that Techflex.
Only then could I figure in any labor costs. You can't go with what the big manufacturer;s charge, because they have TONS of hidden costs the average DIY'er will never have. I know for a FACT that many cable companies charge $500 meter for a cable that costs them $40 to make ... I have toured their factories, and know what is involved, AFTER the set up costs of their machines is paid for, or their costs to the manufacturer's who make their products for them.
But I love to make my own DIY cables for people for only the cost of materials. It gives me the greatest joy when they call me back telling me my DIY cable just smoked their $10,000 cable ! And several well known members on this site use some of my cables, and HAVE replaced their mega buck cables with my designs ..... That knowledge is my "profit"