The current reality is that you should have an SSL for all domains that are actively used. That is especially true with the domain you are using for your hosting or email.
What I would suggest is that you buy a (UCC) SSL certificate and secure your main hosting domain as the base and add all the others underneath. Check out What is a Multiple Domain (UCC) SSL certificate? I think that you would find the (UCC) SSL certificate a good value? I hope that helps?
roy darling *my posts seem a lot shorter in my head
@jwtadmin1 You will need to follow the step to Install SSL certificates just select the type of server you are installing to. If you are using Godaddy hosting most likely your account will have cPanel, WHM or Plex control panel and you can use the following cPanel/WHM: Install a certificate or Parallels Plesk Panel This will allow you to install the cert for 1 of your hosted domains.
As far as securing all domain, This is a personal preference. some people say all sites should be SSL enabled and others say only site that accept Personal information/banking information.
My opinion is only secure sites that handle personal information or eCommerce sites. My reason is the cost of SSL certs and securing several sites can get expensive so that is why I recommend only secure whats needed. However you can get free certs with Lets Encrypt and secure all of your sites there shouldn't be any reason to not secure all domains.