Isabel of Castile was born in 1451. Fernando of Aragon was born in 1452. He was Isabel’s second cousin and it took a dispensation from the Pope for them to be married in October 1469 (with the not yet 17-year-old Fernando’s two illegitimate children present).
Isabel succeeded her half-brother Enrique IV as Queen of Castile in 1475. Fernando succeeded his father as King of Aragon in 1477. By signed agreement they reigned jointly.
The King and Queen of Aragon and Castile committed to support Columbus’ expedition on April 17, 1492. The cost was about 2 million maravedis; a good royal wedding in those days cost about 30 times as much. Isabel did not have to hock the crown jewels to fund Columbus’ trip, though she did offer to do so. (In fact, some were already hocked to pay for the war against the Muslims.)
About half the money needed for Columbus was collected from the profit on religious indulgences in just one province. The Nina (Girl) and Pinta (Painted Lady) were provided by the town of Palos as a penalty owed the crown for a crime. The rest was raised by Columbus himself and he bought the largest of the three ships, the Santa Maria, which was shipwrecked off Haiti on Christmas Eve 1492.
Source: Hugh Thomas, Rivers of Gold: The Rise of the Spanish Emprire from Columbus to Magellan