From the Introduction: "The F-35 Joint Strike Fighter (JSF), also called the Lightning II, is a strike fighter airplane being procured in different versions for the Air Force, Marine Corps, and Navy. The F-35 program is DOD's largest weapon procurement program in terms of total estimated acquisition cost. Current Department of Defense (DOD) plans call for acquiring a total of 2,456 F-35s for the Air Force, Marine Corps, and Navy at an estimated total acquisition cost, as of December, 2019, of about $397.8 billion in constant (i.e., inflation-adjusted) FY2012 dollars. U.S. allies are expected to purchase hundreds of additional F-35s, and eight foreign nations are cost-sharing partners in the program. [...] The proposed budget also requested about $1.7 billion for F-35 research and development."
CRS Report for Congress, RL30563
Congressional Research Service: https://crsreports.congress.gov/