I came across a case study of someone who is doing this as a part-time business, yet earning over $5K a month. He is working in the internet marketing/online marketing niche.
And the best thing with this method is that it is simple enough and most people can do it, even those with no marketing experience.
You need first to find a PLR software. Although this might take some time, you can easily find one. Make sure it is effective because you will build a reputation using that.
Why have I recommended PLR software and not PLR videos or eBooks? Because software is perceived to be of higher value. This means you can charge more, and even if you will get fewer sales, you will reach your income goals easily.