You have 2 scenarios:
Get the 80 nodes, do it all yourself by setting up 1 system, then do a mass image deployment using software like Symantec Ghost or Arconis Snap Deploy.
Get 1 system from the supplier, load the system to your specs (or have them do it), have the supplier mass image the systems for you. The costs involved depend on your software requirements.
The advantage of you doing the master image on your own, and maintaining your own image server (even as a virtual machine so as not to have it running when you don't need it) is that you will have your own RE-deployment option in place if/when you need to re-image a system down the road for a number of reasons that would require it.