The idea is quite simple, you have to be willing to spend a little bit of time on research, and some time with the sales rep. I spent around and hour on the phone (most of it was hold time) with Lowe's and save almost $50 on a gas range off the lowest price I could find!
Here's a link to Best Buy's price. At the time of this posting, it was on sale for $494.99, down from $549.99. Best Buy offers free shipping to Store. To ship to my home would cost around $60.
Lowe's sells this for $599. Lowe's offers free shipping. Their best price guarantee says that they beat any price by 10%.
I called up Lowe's and mentioned that Best Buy is selling it for $495. The Lowe's rep told me that Lowe's doesn't match sales prices, but they would sell it to me for $495. I answered that I may as well buy it from Best Buy if that's the case. So she responded with: "well I can give you a one time courtesy of 10% off the $495 - I just need to confirm that with your local store." She confirmed that with my local store, and I'm expecting it to come.... by Feb 13th (It's on special order). I asked them if they can expedite it, they'll get back to me tomorrow.
I asked Best Buy if they can match the price match. The said they can't but they'd offer free shipping. (I think you can get free shipping on anything, at most stores, if you just ask for it.)