Need easy installation binary.

I am the IT guy for a small-medium sized company (80 employees running 60 computers). I currently have several versions of Norton running on the computers. Some with regular AV. Some with NIS. Some with 360. As the licenses roll off, I will be converting all to NIS. 

 

That is the back-ground. What I am specifically looking for is a place to download an installation binary that allows me to bypass the trial. I want to be able to buy licenses as I need them (from my computer), and then install them in the field using an .exe file from my thumb drive and the appropriate license.

 

I have been looking high and low for a place to download the installers. I managed to get one by downloading the trial from download.com, but it hassles me with a trial account instead of letting me just input the license key. 

 

Also, I am hoping the place to find the installers is easy enough that I can download new builds every couple of weeks so the first LiveUpdate I run after installation is minimized.

 

Any information would be helpful.