Is there a cost for bussiness to use Debian?

[Steve Cottom <lui_meow@iprimus.com.au>]

Hello Web master,

I am doing a cert 3 in network admin.
At the present I am doing an assignment, which is a mock scenario that I 
am working for a company. The company has asked me to compare several 
different Operating systems for: 1 HP proliant server and 100 HP DL530 
workstations.
I have to present my findings and make a recommendation on which OS to 
use and why.
I have been told that Linux is free for personal use but businesses must 
pay, I need to comfirm this for this situation.
Any information you can supply would be much appreciated.

Thank you for your time

Steve Cottom