They're simply too inconsistent with character and lore, and even Joss claims he "forgot" major lore points (but I don't believe him when he says he was personally involved, he just sold the name rights, and was not allowed to say he just took his money while moving on to other things until the company needed him to reassure readers that he actually was involved when he wasn't). I understand that if you're into Spuffy then you'll really love "Season 12."
Ultimately, I consider them a different universe from the TV show much like how I see the different X-Men comics, movies, and cartoons as all being different universes.
And there's better fanfiction. (I just remembered one where Faith was a new personality of an amnesiac Daria Morgendorffer, that was fun, and STILL a lot less silly than the comics! I don't think there was ever an ending to it, but I remember enjoying the read when I found it like 10 years or so ago.)
As for reading them for free...I used to be able to do so (at least some of them) even years after an issue. Maybe one still can (some will have comics from decades ago, at least they used to, I pretty much stopped going after I stopped playing role playing games which often doubled as a place for RPG players).
Library ILL (Inter Library Loan) and another program (where they'll buy the book, including say a season wrapped up in one or more covers so it's more of a graphic novel) as long as it's under $50 used to be an option, and might still work here. If it's out of print and people are selling them for like a hundred bucks (sometimes blatantly stealing them from the library to do so) then you'll be out of luck there, but it seems worth asking.
I hear Faith & Angel are different and might be something I like (feeling more like the TV show and unnecessary to read the other comics to follow along), but haven't even glanced at them.
I have liked some comics that are parallel with the show (one in particular even feels like it should be a TV ep rather than a comic book that links season 5 to 6 neatly). And from what I gather, the Tales of the Slayer comics are about the same as the text version, and I've enjoyed those (but those rarely, if ever, include Buffy, but I do remember one focused on Nikki Wood).
