It depends, but most of the stuff for the last 2 years has been close to full retail. Some vendors will barter; for instance I got a full set of Mac Straps for dirt cheap because I brought the guy at the booth a beer
There is also much to be had on the runs: On the JKO Pritchett run, Poly Performance was handing out discount coupons and we got lots of cool gear from PSC and Pirate4x4. Lots of cool prizes were raffled. On another run, the guys from Eaton saw my Detroit sticker on my jeep, took a bunch of pics and gave me a DEEP discount on a Detroit locker for my son's TJ the next day at the show.
Many lift vendors use the show to showcase their product lines rather than sell, and most have no real inventory on hand. I have seen much better deals in the vendor section on this forum.