Associated press file photo Online prices for everything from food processors to flat-screen TVs can fluctuate by hundreds of dollars, from site to site, day to day, or even hour to hour. This undated photo provided June 1, 2012, by Target Corp. shows one of the T-shirts target is selling to raise money for a group working to defeat a gay marriage ban in Minnesota. The Minneapolis-based retailer is taking heat from same-sex marriage opponents in its home state, where voters will decide this November whether to put a gay marriage ban into the state constitution. (AP Photo/Target Corp., Paul Weber)