Which version of OSX do you have right now?
I am not sure what you mean -- Your question states that you want to upgrade to 10.6.8 but you stated you have 10.6.8 so what is your issue exactly?
A new desktop computer can be purchased around $300-400 and a laptop is around the same. A new Mac computer is a lot more around $900+
What happens when you try to edit the address book? Are you given an specific error message?
What phone number did you call?