I knew some of the guys who tracked Pioneers 10 and 11. They were civil servants who did it on their spare time. The Deep Space Network (DSN) would point an antenna at Pioneer 10 or 11 when it had nothing better to do.

$4.2 million / year is bogus without doubt. My guess is someone took the total cost of running the DSN and divided that number by the total number of hours listening to interplanetary spacecraft and then multiplied that result by the total number of hours listening to old spacecraft like the Voyagers. NASA has gone completely nuts over "full cost accounting". This is just another example.

Gary