Interesting topic. I agree with a few posts that suggest that an 'hourly wage' makes little sense for the primary business owner. One of the things I learned prior to starting my consulting firm almost 20 years ago was to stay away from 'hourly billing'. Yes, lawyers get away with it, but to me, it has nothing to do with the 'worth of the product'.
Put another way, I charge my clients for the 'worth of the product', taking into account supply and demand and my 'brand worth/reputation', etc. For some of my projects, I make well over $1,000 an hour (since I have some procedures down to an art, and am very efficient). I'm sure there are some projects that I make less that $100 an hour (luckily rare!). NO client would pay $1,000 an hour for my services if I billed that way, but many would pay $5,000 for a very worthwhile deliverable (even if it only takes me a couple of hours to do it), and it is none of their business or concern how long it takes me to do that.
So, it makes little sense to set an hourly wage for something like bass building (again for the primary owner/luthier). The price you can get for a bass is set by competition, and any sort of brand equity you have built with you name.
Like any business, if you are a luthier who works like crazy, and at the end of the year, can't make a decent living by subtracting his/her costs from the (price x number of instruments sold), then it is time to go out of business (which I assume many do).
Don't know if that even adds anything to the discussion, but it is one I often have with people new to starting up a small business. Unfortunately, most of these people have no business training and shockingly don't really understand the accounting/marketing concepts necessary to run a business efficiently and make a decent profit (or know before-hand that there is no chance to make a decent profit).