Outside of the bars, these are the next highest cost part of the dual cam solution.
You can in fact get replacement parts for the dual cam system from Reese or one of the resellers out there. If you could get this for around $25 or less (stress the less part), I think one could put together a dual cam system for less than could be bought new. Keep in mind, before metal prices went through the roof, I paid between $150 and $175 delivered for the dual cam system, new. Here is a Internet vendor that sells the whole kit for about $200 shipped (minus the bars):
All Reese Sway Controls | Drawtite | Reese | Hidden Hitch | Blue Ox | Rola
eBay also has the bars from time to time as well, but be warned that you really need to do your homework before buying the bar sets. I started off with 1200lb bars with my Chevy sedan, then when I went to the Suburban (3/4) ton, there was nearly zero deflection on the 1200lb bars. Eventually, I went down to the 600lb bars and the dual cam became more responsive with the firmer suspension 3/4 ton Burb. I got 2 sets of bars off eBay...800lb and 600lb both for less than $40 shipped, each. The price on the bar sets new starts at about $150:
Draw-Tite Trunnion Spring Bars (600 lbs.) 6662
There are a number of Internet based sales, I just used this one as a reference.