There are a lot of non-Apple Mac resellers.
Downward price pressure from competition would come from a PC that's as good as a Mac, including the overall experience from purchasing, to unboxing, to setting up, to using to support.
Resellers are different though. They’re not going to undercut Apple’s prices, not the way eMachine undercuts Dell. The “just as good” thing is entirely subjective. The Mac Cultists will never say PCs are anywhere near it, which is one of the reasons Macs and PCs really don’t compete with each other, too much religious belief on the Mac side. PCs behave very nicely for me, nicely enough that I’ve never even contemplated switching, because I experience exactly none of the problems the Mac crowd says they fled PCs to avoid.