I have heard this as a justification for continued spending for space exploration but have not been able to verify the claim.
Not to discourage further attempts, similar thing has been asked before with few attempted answers
Other then the top answer by /u/Yawarpoma that gives the cost of the voyage for the Spanish crown after which there is also a discussion of problematics of converting to modern currency, further down there is also /u/davratta with an answer that gives more info on the cost of apollo space program
A similar question was asked and partly answered by /u/Yawarpoma here.