Why are some DNA tests only $99 ?
 

I know they aren't valid in court because they are self collected, but are there any sort of laws governing DNA labs. I just worry about the validity of the $99 tests...

I would check what kind of accreditation the lab has (check with your state government website).

Some labs are cheap because they have such a big volume of samples to process or some are upstart labs, so they offer deals to undercut the established labs.

But you are a smart person to recognize that questionable deal:-)