If you are using Pay Per Click advertising to drive traffic to your landing pages, you may want to consider using different marketing copy based on your different keyphrase bids. It's a little extra work, but given the prices of PPC traffic, it could be well worth the time.
Let's say you are promoting, a cheap but good quality product - let's call the product a "Flomble". Some of the keyphrases you are bidding on may include:

• "discount flombles"
• "quality flombles"
• "discount flombles cheap"

Given that, you may want to implement 3 different landing pages, one that focuses on the financial benefits of purchasing through you, the other on the quality of your product/after sales support and the other page a balance of the two. Relevancy of ad to landing page copy is very important in terms of PPC effectiveness.