A registered DIAS I think sells for about $10,000 +/-. Note, they do not function exactly the same way as an M16 auto sear. The auto-sear does not operate during semi-auto fire. The DIAS does affect semi-auto fire. Also, the DIAS needs to be fitted and timed to work properly. None of this is a real big deal, but there are differences.
When you pay for a Registered DIAS, you are not paying for a small .5"x.5" chunk of metal....you are actually buying a license to own and operate any one of the modern M16 type rifles in many different calibers.