$50 / user / year - still not insane but I know it's put people off in the past.
Now, the median salary for thos 100 employees is most likely at least $3000, so you are paying them collectively $300,000 a month. That represents 0.016% of their salary. Do you get where I'm going with this?
What then? Of course no company paying $300,000/month is going to care about $50/user/year.
Edit: Clarification
5/3000 = 0.16%.