Its a hard question to answer, and you need to be specific about which add-ons. A DAC, after all, is an entire additional component. On the other hand, the chassis, jacks, power supply etc are far and away the most costly part of any component - so there is clearly economic of scope at work here. But a good DAC is not cheap to add. A cheap DAC ...well . is :-)
IN small volumes everything costs if its done well. But lot fo the cost is a fixed investment in engineering and tooling.
As you see, its not a simple question. Just buy what gives you what you want, and provides good value (sound/dollar). If the bets sound/dollar has gee-gaws, who cares?