it depends on the kind and the size of the demo. if it is work related and my boss is breathing behind my neck than usually about a week otherwise about a month.
Borland C++ Builder or Borland Delphi
The rad tools in Borland tools are extensive and very easy to learn and use.
I would say a couple of hours with someone familiar with the tools would not be a problem.
I would also suggest that any rad tool worth its salt should do the job in a few hours, its just a demo!
While I'm at it, be careful how good your demos look, always leave something missing or something out of place. To most users a good looking demo means that the program is 80% done!
Well, your example is not very aesthetically pleasing. So I didn't bother looking at it very long.
Why? Because if you are going to do demo something, do something interesting. You have to capture people's attention. So rather than some web page that fronts a db, give me a use-case I can sink my teeth into.
This is why being able to whip up a demo quickly is not all that useful in and of itself (IMO). The hard part of an app isn't the execution of the idea, it's the idea itself and the refinement of it that is the long pole.