The short answer is, you can't. Unless one of the versions price is free, which is what a majority of apps are. Any pricing difference is going to alienate a certain percentages of customers.

Think of alternative ways that you might accomplish the same goal, which is to get the highest price for your product. Release lite versions which have different features and use analytics to track which convert better. Another solution would be to add the features as in app purchases, and let the marketplace decide which they prefer.