You can sell your ebooks through Amazon's Kindle program or Apple's iTunes Connect, which gives you access to a large majority of the digital-book reading market and the barriers for entry are incredibly low. You don't need to invest lots of money to make this happen, but you do need to invest lots of time, not only in writing the ebooks, but in marketing them as well.
Using a food delivery service can’t necessarily earn you money, but it can help you save you money if you constantly find yourself throwing out half the food you buy. Food delivery services send a box of food every week with new, sometimes unique vegetables, meat, fruit, and so on. If you don’t have time to shop and want simple meal-prep that leads to a good meal, a food subscription service may be perfect for you.