Basically, as many as you can manage. The higher the ROI, the more expensive a potential customer will be; and the lower the ROI, the less likely they are to pay to get leads. Let's imagine for a moment that I've been generating leads for your business for a month and I have a pool of potential customers that are perfect for your business. Here you can see that potential customers from Source A not only generate more revenue in their first year, but they maintain their income-generating value better than potential customers from Source B in subsequent time periods.
And yes, losing money, which is why I recommend selling potential customers with this method if you have experience in the vertical market. The value of a potential customer varies depending on the lifetime value of a sale compared to the cost of obtaining that sale. You may have 20 or even 200 or more sources of potential customers, and you can divide your “archived time” into a larger number of more detailed groups. I've read and heard (from a well-known industry analyst firm) that best-in-class companies close 30% of qualified sales leads.
However, this time, you have control over the lead if the customer can't close it for X days. Potential customers are a fundamental element for all businesses to grow, but they often don't arrive the way they should. There are quite a few programs, called CRM (customer relationship management) systems that you can use to track leads, contacts, sales, and more. This is in addition to the original payment made by the customer who bought leads exclusively in the first place.
Therefore, you must come up with an efficient plan to keep those leads and convert them into loyal customers. Let's say you have two sources of potential customers: the first (Source A) is the people who provide their email addresses to download a technical document on your website. It's also good to know the required number of potential customers before moving on to planning your digital marketing efforts. So, instead of setting your marketing budget based on a total volume of dollars or simply an overview of things, take the time to calculate the value of each potential customer and execute your marketing based on the number of potential customers and return on investment.