I too noticed the angle difference in the inner brackets, although I took the route of trying to elongate the bolt holes where the bracket attaches to the frame horns. I suceeded in minimizing the uppward tilt, but didn't eliminate it completely. I noticed recently that the upper lip of the bumper is begining to climb over the notch in the lower edge of my RS bumper. Looks like i'll be pulling it off this winter and modifying it again.
As far as cost goes heres an original GM $76 dollar ebay endura bumper on my car. Do a search for enduro bumpers. theres always someone who spells it wrong and it slips through peoples searches. That's how I got mine. i was the only bidder on it too. A few hours with a flexible bumper repair kit, some sandpaper, and paint and it looks as good as it would have coming from the factory.
