Are you using WooCommerce? If so, both PayPal and Stripe are pretty easy to set up. Personally I prefer stripe because their onboarding process is pretty easy, whereas I found PayPal to be a royal pain in the a**.

If you’re doing eCommerce you are going to need an SSL whatever you choose really, otherwise you are likely to lose customers because of lack of security.

Depending on your host, you may be able to get a free SSL with Let’s Encrypt.