It might not be a clever decision to make money out of your high page rank. It looks like Google is penalizing websites who place paid links on pages with good Page Rank.
Google seems to be not taking websites with less than 4 page rank seriously. However, pages with 5 or more page rank are being scanned by Google continuously. If you have a paid link on your PR 7 page and you find your PR drop to two or three do not be surprised. You have just been penalized.
Following Bob Massa of Search King who first started the “PR Ad Network” selling text links openly, Robin Good of Master New Media was also penalized after Google found out that paid text links were placed on their high PR pages.
Google reduced and also removed the page rank on most of the Massa’s network of websites. This was followed by Massa filling a law suit against Google which was won finally by Google.
Google is becoming smarter day by day as SEO strategies get smarter. If you have paid text links on your home page with high PR, it is time you rethink on whether to keep them or remove it. If you are already penalized, remove all the advertisements and try to submit your site again to Google.