The only script not free is the new After Effects script Immigration. The idea is to make it easier for people to donate to script authors, and to aggregate top scripts in one place where you can donate to many authors at once with one purchase. When you add a script to the cart it puts in a suggested amount which can be edited down if desired. Bringing scripts to one place where they have been screened for quality will hopefully improve the whole experience of using scripts.
Here's an excerpt from the About page:
"AEScripts is a repository and marketplace of high-end scripts for Adobe After Effects. Scripts help enhance and automate otherwise tedious functions. They can also help improve workflows and provide automated operations. You will find scripts from the following top scripts writers from around the globe [links added]: If you would like to have your scripts hosted here or have any other questions or feedback..."