Hi Calum, while looking for inexpensive domain names I ran into a lot of catches. For instance, a lot of sites promising $9.99 domain names required you host your site on their servers. That meant you paid a high monthly fee to them. If you intend on just buying a name without needing hosting, you almost always will end up paying $35 a year.
I used to have a .tk domain, but first of all they had the annoying pop up ads, second I hated my page sitting inside a frame, and finally if your page doesnt get enough visitors in 90 days, they take back your domain name. These things suck, and I suggest you go ahead and get a real domain name. I ended up getting mine from
http://www.netsol.com and although many people tell me I could have gotten it a little cheaper, the service is excellent and since they have been around a lot longer than some of the other companies, I had a little more freedom of mind when paying them. It cost me $70 for a 3 year registration.