There are three ways to cut cost while Using AI in Sheets
by default each function call you make is cache for you with no time limit, so next time if the same prompt call is made we can get it from cache than spending your OpenAI credits
=SHEETAI(prompt, maxTokens, temperature, model, cache)
As you can see the last parameter is cache which can be provided true or false, by default true. But if you want to generate different results with same prompt you can set it false.
So Another way is you can right click the cell and copy then paste as value only.
OpenAI offers many models to choose from. checkout https://sheetai.app/blog/how-to-use-different-openai-gpt3-models-with-sheetaiapp