Camburg makes one that is made to have a rollcage biult into it. Powdercoated, spare tire holder, etc.
It's only 1500 bucks. It says they MIG weld it all together, but im not sure how they could ship something like that in one peice, so if you do need it shipped im sure youll have to do the wlelding yourself (They would probably peice it together to leave minimal work for you.)
Only problem is that your box would be overtaken by this unit. Not that you want anything loose back there when your romping around, but if ur using ur truck as a DD, then its gonna take away alot of the usability of ur bed (I like to use my bed as much as I can Haha... yah i know, lame.)
Im kind of leery about the price, seems cheap, so I would hunt down some reviews on this unit. And who knows if camburg isnt hiding all knids of nasty price points; little extra for this/that option. This site would be a good place to start, i think. I can only see it as being a worth-while option (For me) if you were going to build a cage in your cab down the road. If not i would be happier with a more compact cage even if it cost me more.
Its on their website, under Suspension systems, Rear Suspension, Bed Cage.
Personally i agree with Mjp2 the Giant design is the closest pre-manufactured cage to my liking.