The design document of LayLow is an ABSOLUTE must. Don’t leave home without it.
800€ for 20 machines is 40€ per machines not counting the meetings, the planning, the discussions, the meetings again, the document, the changing of mind, the installation of the server, the connection to the Internet, the backup configuration, (the share folders), the testing, the education of the clients, etc… It seems way not enough…
In the design document, specify that they have to pay 75% of the contract after installation of the server and one station and you will see if they are serious.
What is your hour rate compared to a car mechanic’s?
Make sure the client machines are up to date. Some of them might be near a complete disaster. Out of 20 PC operators there is at best only one unsatisfiable one. If you touch a PC and something goes wrong, you will loose a lot of time and who do you think they will blame?
Usually multiply the time you think it will take by at least 1.5 and you will be almost near reality.