So I got to thinking: the Chinese prototype PCB fab houses are really amazingly cheap, enabling creation of prototypes that otherwise Just Wouldn't Happen. On-shore, OSH Park does a good job of this, too, within its limits.
But, for some designs for certain clients, PCB fab can't happen offshore (because Reasons), and OSH Park's pretty gold-plated finish is not allowed (because different Reasons). Which, mostly, leads back to Sierra Circuits: quick turn, high quality, but awfully pricey. (Good, cheap, quick: you know how that goes.)
I check pricing on a medium-sized (for the category in question) board, going for 6 layers, fairly small feature sizes, and a 5-day turn. And, surprise! It's below the 4-layer pricing of a couple of years ago. Not by any stretch of the imagination cheap, mind you, and far more than Seeed or JLC would charge, but entirely manageable if I were building prototypes for a client with the expectation of being reimbursed.
The idea of getting the test hardware done quick is looking like a more plausible business feature for next year and those that follow. Especially if I upgrade my SMT assembly capabilities, as I intend to do once I have proper lab space.
(I have a sporadic reputation for pulling rabbits out of my hat. Taking a (simple) product from suggestion to component selection to schematic to PCB layout to out-to-fab in an hour, for example. Or slipping out of a meeting where a mechanical apparatus was being discussed, and returning with a preliminary implementation before the meeting was over. I should work on doing that sort of thing more consistently.)