I've worked in both environments with raised floors vs ceiling ventilation/cabling.
Either are fine it just depends what your real purpose is. From what I recall most of the
raised floor environments I've been in were specifically for cooling mainframes and
other server equipment, cabling happened to end up going there but that wasn't the
purpose behind it. Plus you have to have to then be wary of your weight and distribution
of systems with a raised floor which sorta kills the fun after a while. New systems need
new bolts and mounts under them etc.
The biggest pain was long power drops which were zigzagging between posts under the floor
here from various previous moves that were "just enough" to get it where they
needed next. Finally it took a long time pulling those out and rerunning them properly,
let alone finding some with frayed wire exposed. Not a comforting experience after
roughly handling them prior to that.
Ceiling runs you end up with the same stuff after years of poor management. Cables thrown
over and under certain other devices (lights, vents, mounts) that after a while are
difficult to track what is where or work around it properly. The worst story I have is at
a leased office we had which had a very large scorpion problem (they warned us every time
we came there). You couldn't imagine the number of doughnut boxes and coffee cans
they had full of their bodies in the break room (I guess they kept them out of boredom and
as a complaint). Working anywhere in that building was unnerving but a coworker and I had
to do a cable drop to the reception area. We're slowly pulling ceiling panels away,
checking around a bit (my thinking was picturing some hive of the stupid things just
waiting to be pissed off and found). We ran the cable but as my coworker was getting off
the ladder he thought he felt something on his back (of course we spent most of our
time there feeling like that). Either way, he threw his shirt off on the ground and was
freaking out a bit when I found him but I didn't see anything. Mostly was just
something we laughed about afterwards.
So anyway, the discussion might be seemingly off topic but I think the point was debating
if one was a better design than the other. Especially when cost is a concern.
As far as finding the materials all I can think of are freecycle, craigslist free section,
or habitat for humanity type stores if you're really set on doing all that work.