Is this person looking for exclusive use of the image, since it is for a company logo? That would bump up the price 5-10x
If you plane to price it based on the size of the company, you may want to state that explicitly in the agreement and set a time frame for use. You can state that the renewal license fee will be based on the company gross revenue relative to the current amount. Don't know if they will go for that, but it would be a way of protecting yourself. Don't forget to make clear that derivative art based on your are is also your art, or at least must have a license to make derivative art based on your art.
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