There is an alternative.
1. Register for a domain name
2. Choose a registrar that lets you customize DNS
settings for your domains.
3. Register for a free hostanme id dyndns.org (e.g. myownpc.homeip.net)
4. Set original domain name's DNS
domainname.com should be CNAME myownpc.homeip.net (normally it is xx.xx.xx.xx i.e. IP address or "A" record)
www.domainname.com should be defined the same as domainname.com
Any registrat based on "enom" API would let you do that. I have used www.active-domain.com in past
5. Download software for updating IP of myownpc.homeip.net whenever you get a new IP
You are all set!!!!!!! And owe me a beer