It isn't a meaningful sample - there is no such thing as an "average" foot, but some feet are more average than others, and some are a whole lot less average. Add your skeletal alignment to that and "average" becomes even more elusive.
I have custom footbeds, for which I paid $275 7 years ago. A lot of fitting then by an expert pedorthist - boot fitter got me to a great place with them. They're in their 3rd pair of boots and will go into their 4th next fall. I should get 10 years out of them easily. If all that cost is spread out over 4 pairs of boots, not that expensive.
LF and I teach at the same area in NH, but don't live that near each other. I've bought from some of the same shops she has used. I've had good success with some of the same people, and far less with others. The bad shops are easy to find, the good ones far less so.
I'm PSIA and get Pro Formed on my boots by the shops. It's a pretty healthy discount up front for me, and the shops make little money on us. That's great for me, but if you have problem feet (and I do) and need extra work (I do), there is a limit to what you can (or should) ask the shop to do as part of the sale. It's not reasonable for me to expect them to lose money on me. Maybe if I was Bode, but I'm not Bode.
I've had enough bad bootfitting and adjustments over the years to truly value the good ones when I find them. That relationship is one that I want to protect and not abuse. Add to the mix the fact that I have bad luck with boots the last several years, and next fall I will be going into my 4th pair of boots in 3 seasons. I went through 2 pairs of Fischer Vacuums 2 seasons ago. The first was defective (not the seller's fault). Pro-formed to me, and he vacuumed the second pair for me on his dime. I had issues with both boots that put me in a lot of pain in one foot over the season, so much so that I abandoned the second pair after they destabilized after being blown out in the forefoot. There were things he did not understand about bootfitting vacuums that were part of the problem, and he was a very experienced bootfitter with a good rep. But I'm not mad at him, his intentions were there. It did not work out for either of us, but I'm not going to badmouth him to anybody.
I went back to Solomons last year. The work that that the seller did for me was expert and accurate, and skied very well. but the liner was defective. Solomon is replacing the boots under warranty, and he will be custom molding both the liners and footbeds again. I will need them canted again and perhaps some more alignment work too. I'm going to ask for everything I feel I need to get the boots absolutely right, but I want to make it clear to him up front how much I value the relationship and that I expect to pay for at least some of his additional work. We buyers should remember that it is a 2 way street from which both parties should profit. The good bootfitters deserve their profit. I like him and want to work with him in the future, so I should do my part.
Finally, I want to say that the bootfitting can only be as accurate as the feedback we give them. The more precise and knowing our feedback is, the better the work will be. Unfortunately, we learn more about what we need when things are bad than we do when they are good.