Mabé pearl (half-pearl) culture provides rural livelihood opportunities in the South Pacific and is a low-tech alternative to capital and labor-intensive round pearl culture. The Kingdom of Tonga is unique among the pearl-producing countries of the South Pacific in focusing on mabé pearl culture using the winged pearl oyster Pteria penguin. The Tongan mabé pearl sector is developing rapidly and stimulated by routine supply of spat to mabé pearl farmers, from the government hatchery at no cost. It is likely that some level of cost recovery for spat supply will be considered as the sector strengthens, but information on hatchery production costs is limited. This study determined the costs of operating the government pearl oyster hatchery in Tonga and developed an economic model to assess the production cost of juvenile oysters. Modeling was based on a single annual hatchery run generating 6,600 oysters from the ocean-based nursery for delivery to commercial pearl farms. Estimated capital cost was USD 19,079 (excluding government buildings and chattels), and the major production costs were hatchery labor (37%), capital purchase and replacement (20%), and nursery labor (10%). Total annual costs for the pearl oyster hatchery were USD 13,263, equating to a cost of USD 2.01 per oyster supplied to farmers in Tonga. Given significant annual profits of around USD 9,338 that can be generated from 100 harvested oysters, there is justification for cost recovery. Results will be valuable to key stakeholders and have regional relevance for hatchery production of high-value aquaculture commodities.