How many credits (Republic credits or whatever) does a Death Star cost?

How many credits (or standardized form of currency in Star Wars) would it cost to build a Death Star?

Answer

Wookieepedia cites Star Wars: Absolutely Everything You Need to Know (a canon reference book published in 2015) in stating that the first and second Death Stars cost over 1,000,000,000,000 (1 trillion) galactic credits each.