Samsung Galaxy S II / SGH-T989

For those a little familiar with how the cell phone market works (though I thought I was pretty informed up until this weekend), is it likely for the retail price of a phone to go up several months after it has been release?

I tried to take advantage of TMobile New Year's sale this past weekend to finally get my hands on this phone but the requirement to migrate to one of their value plans stopped me. That said, the store rep who talked to me stated that the price of the phone was going to go up and this seemed odd to me since the release date was last October. Note sure if she was just trying to make the sale or if what she stated was plausible. Thoughts anyone?