A posted CD in Germany took a day to arrive (when sent from Germany, and there were people who'd send it locally), downloading the source code for a few large packages could easily take a week on dial-up.
Been there, done that.
Been there, done that.
But in 2004?
And remember, if you wanted to customize something you'd usually need not just one program's source, but also the libraries. Downloading all of Qt and most of KDE to customize something and build it from source took a loooong time.
Ubuntu's first release, IIRC
So even if you were willing to spend 10% of your monthly income (which is impractical, but this is an extreme example), it could buy you maybe 1-2 gigabytes of data. Or you could just, you know, order a (source or binary) CD for free or almost free.