Forget the toolbar
PR; it's a pointless metric, used only by link brokers. What IS of more concern are the following metrics :
1) What is the anchor text being used to link to you?
2) What about any text surrounding the link?
3) What is the theme of the linking page? (Determine this by looking at the <title>, on page text etc. Using the Google AdSense test tool can tell you A LOT about how G see a page)
4) How many other outbound (ie to a different domain) links does the page have?
5) What are the themes of those target sites? (SE's tell a lot about the theme of a page by looking at where it links TO)
To answer your actual question, unless the directory is under a "can't pass
PR" penalty, and the fee was small, it was worth it. 100 links is still 100 links. On target links are better, but harder to get. In most niches, there are only a relative handful of sites that can provide killer links, so you have to cast your net wider in any case.
100 links doesn't provide 100 times the benefit of 1 link, but they are better. DOes that answer everything?