Is ERAGON a book worth buying for?

Yes Eragon is a fantasy book, but the comedy is not the same as the books you have listed. I agree with everyone else. Check it out from the library first. It is a good book but it can get a little dry for the typical fantasy sometimes. If you like it enough, then you can buy it, but whatever you do, do not base your decision on watching the movie, it is not anywhere near what the book is like... at all.