Hey,
Finally i can see a truly 100% Delphi project in here, it doesn't happen often ;-)
No 3rd party components are required for this task, i will use only Windows API via JEDI Windows Security Code Library (open source WinAPI headers for Delphi that allows commercial use).
I have a basic demo for listing users ready (user name, full name, privileges (guest/user/admin), last logon time). I can send screenshot and/or executable via chat. My proposal price ($70) includes 4 main functions, or $100 for all of them.