You are charging per request ($0.05) what amounts to about 1M tokens on GPT4-mini ($0.075); i.e. this is 10-100x more expensive than the cost of running the LLM. I don't think it's worth it at that price point.
Edit (just found out this):
"The $0.05 per request fee covers requests up to 30,000 tokens.
For requests exceeding this limit, additional nominal charges may apply."
Hmm ... it's just too much.