Disclosed is a system and method for enhancing value for advertisers by helping them select and initiate the purchase of an advertisement associated with an advertising (ad) words or phrases that have strong semantic relationships to a given context, but which are not necessarily the most popular ad words or phrases with the highest costs. Advertisements associated with ad words or phrases that have strong semantic relationships to a given context, and yet are still cost effective in that their calculated value exceeds the costs of purchasing the ad keywords, are bid for and bought. In an embodiment, the system and method may be adapted to automatically purchase advertisements associated with ad words or phrases when the ad words or phrases fall within a desired price range based on their calculated value. As the prices of advertisements associated with these words or phrases fluctuate over time based on their popularity of the words or phrases, the automated bidding and buying of advertisements may be used to purchase advertisements associated with words or phrases at a price desirable to a given ad purchaser. By automatically purchasing such advertisements, the return on investment (ROI) for an advertiser may be improved.