The source of the expensive cars story indicates it was Tsarnaevs’ friends who had money.
...The others are from Turkey. They all drive nice cars, they all dress nice. Louis Vitton shoes that probably cost $800. They drive Porches and and the Range Rovers, Junior said, adding that the men all had heavy accents.
I dont speak perfect English, but they had heavy accents. (Tsarnaevs) was mixed, kind of Russian and Turkish, he said...
Yes. It appears that he had very generous “friends”.