If you build yourself, not too bad, probably $75 a bumper at most. Just depends on what you want it to look like.
Its pretty much the same as building an XJ bumper.
On the rear, you'll want to have attachments that use all of the original bumper mounts, as well as all of the mounting points for the trailer hitch as well. Something like 3 x 6" steel would be about the right size for the body, you'd want to taper the ends up and forward. I used 2 x 6" steel and welded an additional 1.5" along the top on my XJ bumpers.
One thing with ZJ and XJ rear bumpers, you need to have metal come up under the tail lights to match the body lines, otherwise theres an ugly gab there. Some thin .125 flat stock can be formed pretty easy and welded up.
For those reasons, the larger plate/rect tube/channel style bumpers look better than any kind of round tube on those. Too much unibody, no frame.
Look through posts in this forum: (the first is grandmans rear ZJ bumper, hint hint)
http://www.greatlakes4x4.com/showthread.php?t=11460
http://www.greatlakes4x4.com/showthread.php?t=395
http://www.greatlakes4x4.com/showthread.php?t=6255
http://www.greatlakes4x4.com/showthread.php?t=3368
My own XJ front:
http://www.greatlakes4x4.com/showthread.php?t=3834
I just bent up a new winch bumper for my toyota this weekend. Mainly 1-1/4" sch 40, with some 1" and 2 x 6" channel. Came out nice, except the red fairlead looks like some creepy mouth, so its getting stripped down to bare aluminum again.
