You source a product, you develop a marketing approach, you find a customer, you sell the product.
Next you get 10 times the same product, use the same marketing approach, find 10 customers and sell 10 products.
At this stage it is easy to believe the next step to be: Find a new product.
It is not.
You need to do more of the same unless your marketing has already reached 100% of the potential customers.
Have you reached all your prospects yet? If not, carry on as it is faster, cheaper and more efficient: every time you sell another one of the same, you get better at it.