The rule was originally set with the 4th gen Koni DA as the standard for the price limit. You can get Mustang Koni DA’s for about $450 each but not sure what the current pricing is for the GM’s.

The AST’s were made back around 2007 specifically for CMC with the price cap in line as you could buy them for $400 each which was the limit back then.
I know you can’t buy them new anymore but I got my AST’s rebuilt last year for $950 for all 4.

If you have any other suggestions for dampers you are looking at please let us know so we can consider them for a rule change. Thanks!!