In my expierence with WM I have had no problems price matching. Just make sure you have the ad, and the exact same item. Also be sure that you are buying it during their sale time. For example if Target's sale for XXXX item starts at 11pm then you can't price match that item until that time.
This is the expierence I have had with my local WM, so I am not sure if that is the same everywhere :-)