Public pricing for hosted-payload service in low Earth orbit is sparse and difficult to compare across vendors and form factors. Commercial orbital stations, dedicated microgravity operators, and most CubeSat platform vendors do not publish per-volume or per-mass rate cards; quoted pricing is typically gated behind multi-week NDA-bound procurement conversations. This paper develops a defensible bottom-up cost model for hosted research payloads aboard 3U, 6U, and 12U CubeSats — the three form factors that collectively accounted for 99.9% of CubeSat-class launches in 2024 [1] — covering the complete mission lifecycle from concept through deorbit.