I so like my web domain register that I also host web sites, web email, and also web SSL certificates, on it. The website hosting is shared with Cpanel.
In year 2022 I bought a multi web domain SSL certificate from my web domain register, valid until year 2027 (I didn't know CertSage back then).
I currently have two websites, example1.com and example2.com.
My current SSL certificate has the place for three Subject Alternative Names (SANs) and is currently set this way:
example1.com
www.example1.com
example2.com
I have asked the hosting support staff to add one more SAN which is www.example2.com but they nicely require about 30-35 USD. Isn't that a bit odd?
It's not a general request for any SAN such as a bare web domain or a Cname web domain or a Sub web domain, but particularly a Cname web domain just to be elegant (if the first website has one, so will the second website have one).
I know that an extra SAN for a Cname isn't critical because most people nowadays don't type www. before the web domain of a website but still, not having a Cname might cause some minor SEO problems or just won't be elegant.
In your opinion, how should I proceed? Thanks in advance.
You could consider switching web hosters altogether. These days, many web hosters provide certificates free of charge (since Let's Encrypt is also free). Otherwise, you could ask your hoster what other plans they have, maybe something else is cheaper. If you want to keep them and they don't offer you alternatives, you will have no choice but to pay whatever they say - the reseller prices are typically not controlled by the CAs.
If you can install your own certificates via cpanel, you could also consider getting a Let's Encrypt certificate entirely free of charge and install that yourself, ditching whatever cert you currently have.
Just use CertSage to acquire a certificate (or two) with all the (sub)domain names you want.
The reason they're charging you is because they need to generate an entirely new certificate. You can't modify the (sub)domain names covered by a certificate any more than you can unprint a paper document.