Yes, the profit is your fixed profit margin % . Ther profit margin with PPC will vary wildly and varied so as a rule of thumb you use the fixed margin for your Sales Planning Forecasting.
For your product – as the top seller is selling at $ 17.99, you will not be able to compete with them at a $29.99 price point. But you can compete with other sellers who have a price of around $29.99 or above.
You’ll need to assess if their volume and sales opportunity is ‘enough’ for you. If you had two different product ideas to compare against, you can decide which one will help you reach your SMART Goal. The product idea you have is certainly not a bad one, you just will need to decide if the profit per month/year is what you need to grow your business. As it takes the same time to launch a product, it’s great to review two or more Product ideas at a time to work out which one deserves your time and effort and which one will make you MORE money. So you prioritise your product ideas based on investment and money back. Does that help and make sense?