Here are the instructions and you can see the side plates in Step 8:
http://qnuwm.rpstd.servertrust.com/v/vspfiles/instructions/R3010.pdf
Is there a chance that they are bolted on already to the bar? At the ends of the bar is there a circle, and then 2 round hex bolts holding on a small metal piece to the bar?
BK is really good to work with and they might be able to hook you up with just the plates and hardware (they sell a hardware kit already but you could get it cheaper from a place like Fastenal, I can give you the sizes tonight if you need), and I would file a claim on the seller if you did it through paypal/ebay and have them cover it for you.
Contact info for BK is here:
BKAuto.com - Brey-Krause Performance Driving Accessories
You can call them and ask to speak to an engineer and there is a chance you may talk to the guy that designed the bar. I have called them a few times with questions and they are always very good to talk to.
Steve