I got a free month's play in Everquest from a magazine cover, and then paid about £10 sterling a month for several months after that (not that expensive if u are online a lot). It's fun to play but oh so slow to progress in trades and higher levels.
The Dark Age of Camelot is similar in price and the graphics are good but I think it suffers from lag more than EQ (which also has bad lag sometimes, particularly in certain zones) and is generally not deemed to be as good as EQ (by EQ players anyway

). I like the idea though.
These games have Guilds which are similar to Clans in that you help Guild members to progress and you band together to complete the more difficult quests.
I think that Camelot is more geared to player vrs player combat than EQ (on most EQ servers players fight against computer controlled monsters and you only have player v player combat when both agree).