In other words, this site is pretty safe...
I keep on getting "This Apple ID is not available" on my iPhone ? what does it mean and how do I fix it ?
You are getting this message because iTunes is confused about your Apple ID and password. If you ask me, it is a bug with the way iTunes handle the verification process.
I also noticed that it happens after I try to restore.
The easiest way to fix it (worked for me perfectly), is simply to go to http://iforgot.apple.com and change the password.
Please let us know how it goes. Worked here on my iPad with no problem at all.