I realize values will vary highly, so I might preface that I'm in the
Northern California area, but....
One of the costs associated with Linux tools is training. Which if you
think about it, is really an investment in staff. Which then amortizes
in a manner strongly dependent on employee retention.
While I've worked in tech environments with 20%, 50%, or even 200%
(yes!) turnover, I suspect that most educational settings have a far
more stable workforce. Say, 5-10% a year, and likely the lower end (one
reference cites 6% for Tennessee[1].
Which means that if you have to engage in retraining, ten years down the
road, you've still got 50% of the staff around[2].
Contrast with PC hardware, assuming a service lifetime of five years
(probably typical for educational environments). If you're rotating out
HW annually, that's a 20% rate of age-out on your investment. Given the
proprietary industry's typical "HW/SW" upgrade lock, and product
lifecycles of 3-4 years, that also means you're probably looking at
maintaining and supporting at least two major versions (and likely 3-4)
on your network.
Message: training costs are an enduring investment in staff. Software
and hardware investments age out far more rapidly, particularly in the
public sector.
Peace.
--------------------
Notes:
1. "Tennessee, for example, annual teacher turnover averages about 6
percent" http://www.nga.org/cda/files/010902NEWTEACH.pdf
Another source suggests 10-15%
http://www.principals.org/news/bltn_teachshort0602.cfm
2. And while it's not likely safe to assume that teachers never forget,
it *is* pretty likely that with training plus constant use, they're
pretty familiar with the system(s).