Yeah, I bought my Honda Fit totaled and had to fix up the whole front end (not engine stuff though thankfully). I bought the new bumper wholesale from a Honda parts dealer in the US (I'm in the US as well). It didn't come painted, however, so I had to take it to Maaco and have it painted. They thankfully had a sale at the time of $150 for painting bumpers at the time. The bumper was like $250 shipped, and the snap connectors were an extra $20 maybe USD. So, that's a $420 estimate just for new parts - I have no idea if you have foam underneath that needs to be replaced as well.
You really should be able to get cheaper than that. Just check
http://www.car-part.com/ for Chevy Malibu bumpers in your area.
And if you don't have anything against just leaving it be, that's the easiest way to go! It's the back corner, so mostly cosmetic, since the rear bumper is meant as a protection against direct rear impacts.