Let me make sure I understand what you are saying and correct me if I am wrong.
You have a page that does very well in terms of sales and is showing up number 1 in Google for a relevant search term but the PR is not that high? Is that right?
If so why are you worried about toolbar PR? You are getting good converting traffic and that should be your primary concern. Would you rather have a high PR site that gets no rankings in the SERPS and does not convert? I know what I would choose. Keep doing what ou are doing and ignore the toolbar PR.