I've actually done alot of home bumper repairs. What you need is some sort of super glue to secure it first, and then you would need to use some fillers to fill the cracks. Once the filler is done drying. Get sand paper to smooth it out. Afterward, just spray on primer, sand, base coat, clear coat. This should be around $70 in supplies. Looks practically perfect.
I actually did a similar thing for filling my bumper license plate holes, and a little boo boo that I got on my rear bumper.