Anyone know what a rear bumper goes for?

bitemarks

This is a ridiculous scenario, but my girlfriend, while trying to get something out of the glove box, managed to release the parking break and roll the car backward down the driveway into a van. It looked pretty bad; I thought she totaled the rear end for sure. To my surprise, it doesn't look all that bad. There is one large dent, in the shape of the van's wheel well, but it's not very noticeable unless you're right up close or run your hand against it. She doesn't want to spend the money to have the plastic bumper replaced, but I take pride in the look of the car and it's bothering the hell out of me.

Sorry for the long intro, but does anyone know how much the bottom plastic piece that sits over the rear bumper costs if I were to have it replaced? Also, is it just that simple of a replacement or is it more involved than I'm even aware of?

Thanks!