How important is a Linear Power Supply Versus a Switcyed one?

Most of these small audio manufacturers have commensurate small volume. To that end, they are paying quite a bit for components, and an arm and a leg for assembly. What you can build 100,000 of for $10/each, can cost $100(or more)/each, to build 100.

I wonder what that represents in actual dollars. Double sounds high, but if its $20 versus $10, does that justify $350?

At almost any power level, a switch mode power supply will be cheaper than a linear power supply, not to mention more efficient and hence cooler. if standby power is important, they can also superior for that  (think always on waiting for a remote). Of course, they are also smaller if not much much smaller for the same amount of power.

Noise comes down to architecture and of course making the design trade-offs for low noise, which usually means giving up efficiency and increasing cost. A switch mode supply may create more high frequency noise on the AC line, but it can also create far fewer high current harmonics on the AC line at audio frequencies and have much better power factor and much lower THD on the AC input.