It depends. Is it just the bumper cover, or the absorber behind it and/or the brackets and braces? You might not know until you remove the bumper cover and inspect it. As mentioned, the cover doesn't come painted "new," but you could try sourcing one from a salvage yard that is already painted your color, if you can find one. The cover, itself, is held on with a number of screws and a lot of clips, many of which will probably break and need to be replaced. Here's a part diagram of the rear bumper assembly, which might help:
http://www.nissanpartsdeal.com/parts-li ... m=850_A001
Rockauto has the bumper cover at various quality levels and price ranges, put they must be painted. You might try Ebay and Car-part.com for other options.