How do I calculate the cost per click that I can afford?

Question

contextual advertising

actually asked a question. I came across one article, I already lost the link somewhere, but the question is open. Actually the essence:
There are impressions, for example - 10,000
There are clicks - 700 clicks
We take a hypothetical conversion - say 5%
we get the number of leads - 0.05 * 700 = 35
Let the average cost per click (we take from the Yandex budget forecast) - 40 rubles
Accordingly, the cost of a lead will be = (40 * 700) / 35 = 800 rubles
Now the question is - I read in the article that you can somehow calculate the cost of a click that you can afford. Well, for example, a budget of 100,000 rubles. I don't know how to calculate

Answer 1

Maybe I'm wrong, but it probably means the calculation of the marginal cost of attracting a lead. For this calculation, we need to understand the margin that a lead brings us, for example, if the margin is less than 800 rubles, then the above conditions (cost per click, CTR, lead conversion) will lead to losses.
Let's take, for example, a margin of 500 rubles from a product, ceteris paribus, we will find out the cost per click that you can afford:
Cost per click = (500x35)/700 = 25 rubles per click, at this cost per click, we will have everything at "zero",
As It can be seen from the formula that the available budget does not affect the cost of attracting a lead.
Bottom line: the cost per click that you can afford is calculated based on the margin for the purchase of your product / service.