Also, remember most directoried get their 'PR' from recripocal linking.
So, while the toolbar PR may inflate, their outbound 'link juice' is lost at the same rate. Meaning your link has a much lower value.
I'd spend time looking for authorative and specfic directories if I were you. PR's will be lower, but you care about making money, not being emotionally validated by a little green bar, right? Also, raid any local-themed directories that Google Places source reviews from (even if Places isn't important to you - I'm still seeing value from these)