It's disinformation because I made a specific claim, and you responded by refuting a claim different from the claim I made.
The costs are relevant because they are one of the reasons why legally acquired FA firearms are not used in crimes. They typically cost about 10 times as much as illegally modified semi-auto firearms of the same model, and involve a more significant background check to acquire than firearms in general.
If there was a legally acquired FA firearm used, the serial number and ownership history would be available within minutes of the time the name and DOB (or DOB and zipcode) of the owner was known.
A Ph.D student in neuroscience shot at least 50 people at a showing of the new Batman movie. He also appears to have released some kind of gas from a canister. Because of his educational background this person almost certainly knows a lot about molecular biology. How long will it be (if ever) before a typical bio-science Ph.D will have the capacity to kill, say,a million people?
Edit: I'm not claiming that this event should cause a fully informed person to update on anything. Rather I was hoping that readers of this blog with strong life-science backgrounds could provide information that would help me and other interested readers assess the probability of future risks. Since this blog often deals with catastrophic risks and the social harms of irrationality and given that the events I described will likely dominate the U.S. news media for a few days I thought my question worth asking. Given the post's Karma rating (currently -4), however, I will update my beliefs about what constitutes an appropriate discussion post.