It's futile to try to find a general "are they overpriced" yes/no statement. Some are, some aren't, it's a case by case answer.
Small batch small manufacturer production in a western country can't be the same price as full scale production in China, makes no sense to compare the prices.
Let's build a high quality 3d printed mod then, shall we.
DNA250c board - 70$ (well actually 80$, I guessed how much cheaper it would get if you buy 500-1000)
small stuff (buttons, 510, gold/silver battery contacts, screws, magnets, bottle) - 10$ (likely more that that)
high quality 3d print of a housing + door - 40$ (includes best materials (glass bead reinforced nylon or alumide) and surface finish on an industrial 3d printer, likely will be more than that)
assembly - 6$ (assuming it's 20 min of someone getting paid 18$ an hour)
That's 126$ for the production of a small series high quality 3d printed (no amateur cheese grade print) DNA250c regulated squonker without any packaging or distribution and then you didn't earn anything yet.
If you don't 3d print but use stabwood or resin instead that won't lower the cost but make it higher.
I'm not saying all expensive devices are made like that, eg some skimp on 3d print quality (looking at you, boxer), some may get better prices for all that, but the price will never ever go down to China prices, you simply can't compare them. I also don't imply the device must be better than a chinese one, that's entirely up to the designer (like the dotsquonk isn't cheap but has some serious flaws), the question was to explain prices and I just tried to get in the rough ballpark.
If you think you can produce a high quality regulated squonker for 20$ - be my guest. Also, I'll buy it