Thanks to Skelf for posting that.
IMHO, people need to be aware of this stuff.
As some others have stated, it doesn't only go for instrument builders or small handicraft companies, but for many companies in many branches - often, but not exclusively, small operations that care about their customers and about the quality of their work. I've also seen these numbers for factories, importers, and retail.
Someone mentioned a markup of 100 %. However, IME that mostly is about a retail price including VAT, with the in-price being ex-VAT and before any type of overhead.
As one of many different typical examples for a medium sized shop in Norway or The Netherlands:
in-price ex-VAT: £ 100
in-cost: 4% = £ 4 ==> £ 104
overhead 25% = £ 26 ==> £ 130
income before tax 20% = £ 26 ==> £ 156
VAT 25% = £ 39 ==> £ 195 retail
Those 26 quid are then taxed 48%, leaving slightly more than £ 13 to the shop-owner for doing the work and taking the risks of the investment.
Add to that the market's demand for discounts and other stuff, and the shop-owner is one lucky b* if he sometimes does indeed get those 13 quid on a £ 195 sale.
Me personally, for years I charged £ 30 per hour, but in reality was left with £ 3.50 as an hourly income. Not much in expensive Norway, but it did give me the life style I was interested in, so no complaints.
best,
bert