I suggest you don't buy any course at present, read SP every day by settign time aside, bookmark certain topics of interest, once you feel you have done it try applying the theory and tips. If it doesnt work for you and you feel you are doing something wrong, then ask for assistance and mentorship.
If you don't go after what you want, you'll never have it. If you don't ask, the answer is always no. If you don't step forward, you're always in the same place.
When you believe you can...you can!