I went with a local retailer when I bought my ST earlier this year. Saved a little bit because I paid with cash but did have to pay a bunch in taxes. I rather pay a little extra and make sure the game is perfect then risk damage in shipping. My game had a big hole in the box. If it was shipped that way I would of freaked out but the game itself was fine. The retailer unboxed it in front of me and we both made sure everything was perfect in cosmetics and gameplay.
How much can you save off retail? Nobody seems to put out any real numbers. My understanding is that the profit margins are pretty slim on Sterns so not a whole lot of wiggle room.