BACKGROUND: The HIV Prevention Trials Network (HPTN) 083 trial demonstrated the superiority of long-acting injectable cabotegravir (CAB-LA) compared with oral emtricitabine-tenofovir disoproxil fumarate (F/TDF) for HIV preexposure prophylaxis (PrEP). OBJECTIVE: To identify the maximum price premium (that is, greatest possible price differential) that society should be willing to accept for the additional benefits of CAB-LA over tenofovir-based PrEP among men who have sex with men and transgender women (MSM/TGW) in the United States. DESIGN: Simulation, cost-effectiveness analysis. DATA SOURCES: Trial and published data, including estimated HIV incidence (5.32, 1.33, and 0.26 per 100 person-years for off PrEP, generic F/TDF and branded emtricitabine-tenofovir alafenamide (F/TAF), and CAB-LA, respectively); 28% 6-year PrEP retention. Annual base-case drug costs: $360 and $16 800 for generic F/TDF and branded F/TAF. Fewer side effects with branded F/TAF versus generic F/TDF were assumed. TARGET POPULATION: 476 700 MSM/TGW at very high risk for HIV (VHR). TIME HORIZON: 10 years. PERSPECTIVE: Health care system. INTERVENTION: CAB-LA versus generic F/TDF or branded F/TAF for HIV PrEP. OUTCOME MEASURES: Primary transmissions, quality-adjusted life-years (QALYs), costs (2020 U.S. dollars), incremental cost-effectiveness ratios (ICERs; U.S. dollars per QALY), maximum price premium for CAB-LA versus tenofovir-based PrEP. RESULTS OF BASE-CASE ANALYSIS: Compared with generic F/TDF (or branded F/TAF), CAB-LA increased life expectancy by 28 000 QALYs (26 000 QALYs) among those at VHR. Branded F/TAF cost more per QALY gained than generic F/TDF compared with no PrEP. At 10 years, CAB-LA could achieve an ICER of at most $100 000 per QALY compared with generic F/TDF at a maximum price premium of $3700 per year over generic F/TDF (CAB-LA price <$4100 per year). RESULTS OF SENSITIVITY ANALYSIS: In a PrEP-eligible population at high risk for HIV, rather than at VHR (n = 1 906 800; off PrEP incidence: 1.54 per 100 person-years), CAB-LA could achieve an ICER of at most $100 000 per QALY versus generic F/TDF at a maximum price premium of $1100 per year over generic F/TDF (CAB-LA price <$1500 per year). LIMITATION: Uncertain clinical and economic benefits of averting future transmissions. CONCLUSION: Effective oral PrEP limits the additional price society should be willing to pay for CAB-LA. PRIMARY FUNDING SOURCE: FHI 360; Eunice Kennedy Shriver National Institute of Child Health and Human Development; National Institute of Allergy and Infectious Diseases; National Heart, Lung, and Blood Institute; National Institute on Drug Abuse; the Reich HIV Scholar Award; and the Steve and Deborah Gorlin MGH Research Scholars Award.