Hi, Tien,
I didn't pay for it. I'd just tried to learn as much as possible and apply it where I can. My reason is that I'm
gardening as a hobby in a shared garden, so I cannot expend money on this.
Also, a
permaculture design is just a framework. You also need to know how to garden, how to build things, and such. The design just informs you where it is best to place things, but then you have to check it constantly, getting feedback. Even if I were to pay for a design, I need to know how to apply the feedback.
That said, it's a lot of time invested in this, so if you don't have the time or the wish for learning, and have money instead, it would be an option.