Choice: Zootool (@zootool) offers a pro account and leaves you a choice for how much you want to pay. The range is from 1$ to 100$. Check out the landing page and the email campaign that are very skillfully crafted.
When you move it to the left (which will be a lot of people’s first reflex I’d argue): the grass in the illustration grows thinner and at 4$ says: “We won’t be able to feed the Rhino anymore, but that’s ok!”
Below the whole payment arrangement, you’ll see the Here’s what you get details.