That sounds like a great idea — $10 seems like a very fair starting point for custom layouts, especially if you’re confident with CSS. A lot of people are looking for personalized profiles but don’t have the time or skills to do it themselves, so there’s definitely a market.
One thing to consider early on is how you’ll handle payments. If you're planning to work with clients internationally or want to avoid the usual delays with certain platforms, you might want to look into something like https://a-pay.one/. It’s straightforward and supports flexible payment options, which can make the whole process smoother — both for you and your clients.
If you post a few examples of your work, I’m sure you’ll start getting commissions soon!