Originally Posted by Custard7A
Anyone can use https, but it requires a digital certificate to be implemented on your server, such as a SSL certificate. Such certificates can be purchased from hosting companies and the like for hundreds of dollars per year. That's about where I stopped looking into that, so the rest of it is over my head as well.
I assume smaller websites just can't justify the cost.
I'd recommend having a peek at what Paypal offers before giving up on your idea.
SSL certificates aren't that expensive, you can get them for a lot cheaper. You just need to have hosting that lets you install a certificate, that is the harder aspect in my opinion. Plenty of hosts do that but it isn't a feature of the entry level hosting plan usually. I get mine certificates from StartSSL
When it comes to ordering and user accounts I prefer the setup where you can create an account or checkout as a guest. That way people that want to make an account can while still not making it a hassle for people who would rather not.