As a freelancer should you invest 1st your money to have good tools and then reach out to your clients OR start small with what’s available online and with some clients and only then invest your money to have access to better tools?
You don't need an expensive platform to sell your courses, however you do need an online platform, otherwise you are missing out. I built my own online courses and I explain in detail how this can be done without a huge investment:
I use WooCommerce and PayPal, neither of these requires any investment. The plugin that I used for building my course costs $218 and it includes lots of additional features, such as lead generation, landing pages, etc.
Offering a small section of your course for free helps you get leads.