They probably cost less than Test Track, too.
I looked around online for an estimate to Test Track's cost, couldn't find anything.
All I do know is that it opened something like 22 months late (they should have worked on it a little longer), and Tokyo DisneySea's Journey to the Center of the Earth uses an 'improved version' of Test Track's ride system.
But that one only gets up to 47 mph, how that's an improvement I'm not sure ...