Dieter Rencken writing in Autosport (access required) has had a long chat with Franz Tost of STR. He has been around the block in F1 on pretty well all sides over the years.
When STR ran RB customer cars about 6 years ago it cost £75 million for a season compared to £90 million last year. Allowing for inflation and the higher engine cost last year that shows that customer cars are not low cost options. At time Red Bull was not the force it was to become either.
Tost does not believe that customer cars are the answer to F1's problems.
http://plus.autosport.com/premium/fe...594.1432368537