Theres no hard and fast rules to follow with pricing Tom. Only you know how much dedication, hard work, promotion and $$$ you put into it. Set your prices and test them.
I have paid over $35 for PR0, simply because PR alone does not sway my decision one way or the other when I am submitting. I do background checks and can usually make a pretty educated decision if the directory will be here for the long haul.
Without having a link to your site your question is hard to answer, although a few here will let you know one way or the other as PR is their only influence.
...and Welcome to Directory Owners.
