A helpful scale.
60F = 15.6C
65F = 18.3C -- Approx winter temp of many US offices
70F = 21C
75F = 23.9C -- Approx summer temp of many US offices
80F = 26.7C
85F = 29.4C
90F = 32.2C
Both approximate temps are based on my personal experience at companies I've worked for. Some companies keep winter temps as low as 60, some allow summer temps to go up to 80, and some keep a constant single temperature year-round.
If there's a single temperature, it tends to be right around 70F.
Some trivial disc check that prevents casual copying but won't give you a support headache would be closer to the sweet spot I think.
Mainframes cost a lot more than 100k, usually a few million.
"How to make a million dollars: First, get a million dollars." -- Steve Martin