High-ticket consulting or coaching: You could sell your own high-ticket consulting or coaching products from your website. You'll still need a website, merchant account, sales funnel, lead magnet and many other items. But you can easily earn a substantial amount of money from each individual customer, making it well worth the arduous setup required. 
Many courses exist (many of which, logically, are offered online) where you can learn the language of website creation and can learn about the details, like how to set up shopping cart systems, security concerns, etc. You will, of course, need to learn about each company you design for. What is the atmosphere of the company that you need to reflect in the website design--is it wild and contemporary, meaning brilliant colors and fun graphics? Or will more classic colors like black, navy blue and maroon be more appropriate?
Because digital marketing has so many options and strategies associated with it, you can get creative and experiment with a variety of marketing tactics on a budget. With digital marketing, you can also use tools like analytics dashboards to monitor the success and ROI of your campaigns more than you could with a traditional promotional content -- such as a billboard or print ad.