That's the driver side mirror, right? I doubt it can be buffed out. If it does not pass the "ball point pen" test (i.e. if the gouges are deep enough for a ball point pen tip to drop in and follow their contours, then the glass is unrepairable. I'm not sure if the glass and plastic backing that attaches to the electric motor is available as a single unit, or if you have to buy an entirely new mirror. If the glass unit is available, that's your cheapest route. However, if it's electroluminescent (I'm not sure if all driver side mirrors are dimming or just the GT/ Touring-Tech), even the glass unit will not be "inexpensive".
Sorry to hear what happened. The first cut is always the deepest.
Edit: Now i'm confused, is the damage to the mirror or the door glass? The more I look, the more I see that the damage is to your door glass. Please clarify. If it's the door glass, it may actually be cheaper to replace than an entire electroluminescent mirror, which i would venture to guess costs approx $500. The side glass installed aftermarket may be cheaper. However, it may not yet be available aftermarket, in which case you're probably at $500 once again if you're forced to go OE. Of course, the pen test applies to mirror or side glass.