Croudis (17) made six birdies to take the title just weeks after winning the New Zealand under-19 tournament.
The pair started with birdies on the first hole but Croudis also birdied the second to take the lead.
He recorded another birdie at the sixth to increase his lead to two, but on the seventh his approach went through the green and he failed to get up and down.
Croudis birdied the eighth to turn two up and went three ahead when Cameron bogeyed the 10th.
Two chips to the 12th green cost Cameron once more, but he bounced back at the next hole with a superb eagle three.
Croudis hit a driver off a sloping lie for his second, to reach the green in two on the 15th to finish the match.
Riho Kanazawa (Cromwell) and Shani Arona (Arrowtown) had an excellent warm-up for next week's interprovincial tournament in Auckland.
In the girls final, the pair finished the round all square and went to a play-off.
They played four extra holes before Kanazawa made a birdie to take the title.
