My thoughts on this? Well, if you really can't afford a domain name, do what you need to do. But, as long as you understand the benefits of having your own domain name. That way, in the future (when you can eventually afford your own domain name), you will know what to do.
Here's a snippet from the FAQ section of Quackit's Create a Website tutorial.
Although it is possible to have a website without it's own domain name, I wouldn't recommend it. Apart from making your site appear "amateurish", there are disadvantages to not having your own domain name.So, if you really can't afford a domain name, don't let that stop you from building your website for now. But you should definitely keep in mind the benefits to be had from registering your own domain name.
One key benefit of having a domain name is that it will ensure that your website address doesn't change unexpectedly in the future. Even if you change hosting providers, your domain name will remain the same.
A domain name can also help your listings in search engines and directories. For the small cost of registering your own domain name, the benefits are well worth it.
If you can't afford a domain name, then you would need to either, host your website in a sub-folder of another website (eg, www.othersite.com/yoursite) or tell people to access it using its IP address (eg, http://74.125.19.104). Not all hosting plans will allow you to do this. The best (and easiest) way to go is to simply register a domain name.
And remember, once you register your domain name, nobody else in the world can.
