How to calculate the patent agency fee?

There is no fixed standard, depending on the price you negotiate with the intermediary.

If he pays 10 thousand, you are willing to pay so much money, fine, at best, he is not kind

If you only want to pay a dollar, if the intermediary is willing, you can call him a fool at best.

The market price is about 1500-2000.

I only quote 600, including: if you don't have a patented technical scheme, I will design it for you.