I had ths dilemna as well, and I was quite proud after many hours I finally made it work.
Here's what you do.
1) Buy your domain name.
2) Go to
http://www.zoneedit.com
Here, you can have a free Name server, up to 5 free.
3) Go back to your Domain name host, and give them the Name server info for zoneedit.
* Now you will have a domain name and a free naming server to go with it. When your IP address changes, just go back into zoneedit and change the directing info.
Or, you can have your Zoneedit point to your No-Ip addy, but I don't think thats a neccessary step, as you still always have to update No-Ip.
Basically, ZOneedit is a site that allows say, anytime someone types
www.y0urwebsite.com it will redirect to your web server at home at your IP.
I did this last night, and it works.