Top of the line expensive parts vs. Budget parts. Is the cost difference worth it?

I get asked frequently "is the difference between this expensive, top of the line part and this budget option worth the price?" This question is applied through numerous parts and especially your overall build. If I'd buy all the most expensive, but best parts, will the cost be worth it over the budget parts? Here is a video from Krikke Airsoft that explains this topic in a way that couldn't have been said better.

For a general overview, skip to 5:56 to 7:54. 20:29 through 22:14 will talk about the if the price difference from maple leaf to PDI barrels is worth it.