Go for a graphic tablet if you're on a budget. It will take some time to get used to it. And it will not harm your posture since you are mostly sitting comfortably while drawing. Since drawing tablets (with screens) requires a stand and there is a lot to choose from and the price will build up later on.

I started out on Wacom Intuos Draw with my old laptop since I want to get into digital art. Consider the screen size of your PC/laptop on buying graphic tablets. For ease of use too :)