The OpenAI fine-tuning api is pretty good - you need to label an evaluation benchmark anyway to systematically iterate on prompts and context, and it’s often creates good results if you give it a 50-100 examples, either beating frontier models or allowing a far cheaper and faster model to catch up.

It requires no local gpus, just creating a json and posting to OpenAI

https://platform.openai.com/docs/guides/model-optimization