As generative AI tools become increasingly integrated into educational research workflows, large language models (LLMs) have shown substantial promise in automating complex tasks such as topic modeling. This paper presents a user study that evaluates AI-enabled topic modeling (AITM) within the domain of P-20 education research. We investigate the benefits and trade-offs of integrating LLMs into expert document analysis through a case study of school improvement plans, comparing four analytical conditions. Our analysis focuses on three dimensions: (1) the marginal financial and environmental costs of AITM, (2) the impact of LLM assistance on annotation time, and (3) the influence of AI suggestions on topic identification. The results show that LLM increases efficiency and decreases financial cost, but potentially introduce anchoring bias that awareness prompts alone fail to mitigate.