Lol I hope that you have to by the disk, cause then it will run faster than a browser and the programers can make a bit of profet for their hard work, but i think that it should be free to play online!
Guild Wars is pretty fun. That is, if you find a good enough guild to go with. Or if you get a good group to do missions and quests with. It makes all the difference. Without a good group the level grinding is just absolutely terrible.
I really don't think it can be on disk. We'd have to have some good money to start with and not to mention a licensed organized game design company to put out the disks.