Is it advisable to create and use your own SSL certificate?

It depends on your site. If it's public and available to lots of users then you should pay to get an official certificate so that your identity is verified and your visitors will know it's a trusted site. If it's a small application, VPN connection or something else with just a few users that won't care, then go ahead and use your own certificate because something is better than nothing to verify they're connecting to the right service.

Technically you should always create your own certificate. (Having someone else create the certificate for you means that they may retain the private key.) You do this when you create a CSR (Certificate Signing Request.) The question you are asking is whether you get it signed by a known Certification Authority. I use a couple of self-signed certificates, but these are for sites that only I visit (e.g., like a firewall I may manage). So if it is just you, then a self-signed certificate is fine. You may wish to keep track of the certificate fingerprint, so that you can verify that when you tell your browser to trust the certificate. If the people visiting your site are sophisticated enough to understand what a self-signed certificate is and if you have some means to verify your certificate's fingerprint with these people, then a self-signed certificate it fine. Otherwise, spend the 20USD and get your certificate signed. If you receive email to the same domain that you want the certificate for, then that seems to be all of the checking that is needed.

If you want to use an SSL Certificate for testing or experiment purpose, then you can go for your own (self signed certificate) SSL Certificate. But, self signed certificate are less secure and trusted. It maybe caught by bad cyber criminals and can injure your app. An SSL Certificate from a trusted CA like Comodo provides highest level encryption and verifies your legal identity by validating the domain ownership and organization detail. Apart from the trust, security always matters. As you said you are not looking for user’s trust, but what about the security. Will you take the risk of hacking and ready to face any upcoming suspicious activities (by hackers)? And you can get a https://ssl.comodo.com/free-ssl-certificate.php also from the trusted CA and you can have a cheap SSL like Comodo https://comodosslstore.com/positivessl.aspxat$7.45/yr and that is affordable. So, I’ll recommend to go for a trusted SSL Certificate instead of a self signed SSL Certificate.

In the most cases, user try to create their own self-signed certificate but its very crucial matter for website security. If you try to choose self-signed certificate then it will be cause for security breaches and it will be huge vulnerability for third party access. So it would be advisable that if you go through third party Certificate Authority (CA) to get your SSL certificate. However, if your intention is not that crucial to protect users information or website data on the internet then you could use self-signed certificate. For further details about SSL certificate importance just have look on this blog post. https://www.rapidsslonline.com/blog/how-do-ssl-certificates-improves-website-conversions