Two weeks or so ago, NCsoft mailed out Nightfall trial codes to Guild Wars players. The codes are for 10 hours/14 days of play time. So maybe you can find someone willing to part with his or her trial code. Good luck?
You can play it for free I think? If you have someone who bought the game, and might have a friend trial key. The trial key is free and its only for 10 hours. I remember a friend of mine giving me a trial key that he got from buying Guild Wars, and I got 10 hours playing it for free.
The way your asking for the cd "key" I dont think anybody will give it to u.
Though if they do, they'll probably want something in exchange. I mean wasnt the Trail keys Limited? or sumthing? eh who knows.