Sam’s Club stores in the U.S. will be offering the 16GB iPhone 4 for just $147 with a two-year contract through Christmas Day, according to a new report. Citing information and a matching screenshot from an anonymous source, Engadget reports that the 8GB iPhone 3GS will see a similar discount, and will sell for $47 on contract until the holiday. Notably, the iPhone 4 price would represent the cheapest of the season, beating out Radio Shack’s…