In today's money, what was the value of a 1492 Spanish maravedí? Satava (2007) estimates that the costs of Columbus's 1492 voyage was 1,765,734 maravedís.
In today's money, what was the value of a 1492 Spanish maravedí?
Walsh (1931):

The author of this work has translated maravedis into dollars of 1929 by reference to statistics on purchasing power in wheat, corn and other staples. Hence his opinion that the maravedi was worth about two American cents of 1929.

According to the BLS inflation calculator, \$1 in 1929 is about \$15 today (2020).
So, if we accept Walsh's estimate, then one maravedi in 1492 converts to about \$0.30 today.
(And if we also accept Satava's estimate, then Columbus's voyage cost 1,765,734 $\times$ \$0.30 $\approx$ \$529,720 in today's USD.)