GKD,
I have paid $25 - $40 to get listed in PR0. ( depending on the owner of the PR0 directory) because if its someone you know as a high PR merchant... his site always get high PR in the end, its worth it. (for example Chris Hoffman)
If its someone you do not know... then its not worth it.
I have also has people pay $50 to get a link on
this site when it was PR0 . I think its because they know that most of my sites always get to at least PR5 in the end