Autozone sells them for less than your local dealer - part number should be ZD-9 for the bullet type connector - I don't know the part number for the spade type terminal ones. When you get them from Autozone they come in a motorcraft package.
I don't know what exactly the difference is between Beru and other makes of glow plugs but they just don't have a habit of swelling the tips - which can make removal fun to say the least. Because the last thing you want is a tip that is swollen and then it breaks off because you need to get the entire thing out of the head because you can't fit a gnats ass hair between the piston and the head when at TDC. You could either break the piston, or at the very least it will pound it into the piston and become embeded. Typically it turns out for the bad.