A digital file costs nothing to duplicate, but that's not what buyers are paying for — they're paying for the time saved or the result it gets them. Price against that value, not against how long it took you to make.
Look at a handful of comparable products in your niche before settling on a number. It won't be exact, but it keeps you from pricing wildly out of step with buyer expectations.
Instead of one fixed price, consider offering a basic version and a more complete bundle — some buyers will always pay more for a fuller package.
Selling the product is only half the work — you also need a store that delivers the file instantly, handles payment securely, and lets you adjust price or add variants as you learn what sells. That's the part Buylib handles, so you can focus on the product itself.