They claim the savings come from the fact that they're basically using the same engine for everything, i.e. a Falcon 9 has a cluster of the same engine used in

They claim the savings come from the fact that they're basically using the same engine for everything, i.e. a Falcon 9 has a cluster of the same engine used in the Falcon 1, and the Falcon Heavy will have three clusters of the same engine. Though I'm sure they don't pay more than it takes to get the talent they want. Why would they?