Testmasters Legality?

I saw on the Testmasters site that they sell the official SAT blue book and even old tests for a price. I am also aware that they only use official SAT tests in their classrooms. They are also the only SAT test prep I know of that distributes official SAT test prep material

Is what they are doing legal?

I don’t understand why Testmasters may sell official SAT tests but students and copious websites aren’t even allowed to generously hand them out.