If I am designing typographic posters, is it okay to base a piece on a famous quote said by a celebrity?
In this case, it is by an author. However I don't think the quote is taken from one of her books, I think it's just something she said at some point.
Is it likely that there could be legal issues if I were to be selling artwork that was based around this quote?
The main concern would be copyright infringement. A quote is typically a very short snippet, and when used as a minor element in a piece of art, the copying would not be substantial, would have no effect on the market for whatever the original was, and is highly transformative, thus it could probably be defended as fair use. That does not mean that you couldn't be threatened with a lawsuit (where you might have to defend yourself), it just goes to the question of whether the author could get a judgment against you.
