"I hear ya, Barkester," but may I
also advance the idea that, with that approach, "your $150 might be for nothing."
The premise that is (sometimes ...) advanced by "certification salesmen" is that, in order to be
[hired | hire-able as ...] "a Linux network manager," you must
[merely ...] "pass someone's test."
If not too many years have yet passed since you were in high school or in college, where "passing someone's test"
was "what you lived-and-died for
at the time," then it might seem very strange to you that, to a rather-tremendous number of people who have the capacity to give you a paycheck, "a piece of paper that indicates that you 'passed someone's test'" might mean ... absolutely
nothing.
When you emerge into the actual world of "employment," there are
no "absolute standards-of-reference," such as a high-school or college
(associate's, bachelor's, master's, doctorate) diploma. At this writing, in this
("not yet a ...") profession, there is no body-of-law describing any uniform barrier-to-entry that you must pass in order to be allowed to "practice." Anyone who says otherwise – or who merely allows you to
assume so without bothering to correct you – is deceiving you.