As some other members have suggested, Facebook is one way to get into e-commerce without a domain name and a website. I have dabbled a bit with Facebook and here are some things I have learned along the way:
1. Facebook is free.
You don't have to pay to be a member. And you don't have to pay to use it. Of course, you need your internet connection.
2. Facebook is reliable.
It hardly fails. Or, put it another way, relative to many other servers, it's a whole lot more reliable.
3. Facebook is growable.
Yes, that's a weird way of putting it but that's actually what happens. Facebook is free, true, but if you want to spend some money, you can pay to boost your posts. At a very low price. Something like $1 to reach 1k people. Or $1 to get 1k video views.