You get what you pay for - there are no free RPGs I would spend my time playing.

Guild Wars is not free - you buy it like any other game, but it does not have a monthly fee. Pindar asked for opinions on it here recently - have a look at his thread. (I hated the game).

I agree with Whacker, if you are cash constrained and want scores of hours of high quality RPG gaming, consider some of the older CRPGs. I would add Baldurs Gate 1 & 2 to his list - you probably can get a compilation for a ridiculously low price and spend 100-200 hours playing it (and that's just on the first run through!). [EDIT: Kek beat me to it!]

The best recent CRPG in my opinion is Vampire Bloodlines.