I am going to disagree with yo, but with one caveat. Every project should have concept generation (several concepts), concept refinement (1-3 concepts) and concept finalization (1 concept). I’m assuming the 24 hours on the 1 concept is for finalization and some refinement only - no generation or refinment of other concepts.
If my assumption is correct, only charging for refinement and finalization is a dangerous presidence. What happens on the next project? If you charge only $X on this vase because it is “complete” but you want to charge $X+Y to include your other ideas on the next vase, as the company owner I would ask what is different between the final deliverable that you want the extra $Y. If vase 1 and vase 2 are essentially the same, why would I pay more the second time? Raising price is extremely difficult without adding value.
If my assumption is incorrect and the 24 hours includes generation, refinement and finalization, disregard my gibberish.
Also, Lmo, cost and price are unrelated. Price is determined by what the market will bear. Cost is determined by consumption of resources. If your cost is $10K and the market will only bear a $2K price, no one will pay the $10K. And judging by the negative profit margin in that instance, you won’t be in business for long.