I got loads of them from e-bay...there is a company called Bibz and Bobz (Im useless with links if not I'd link to them for you!) and they make them in every possible colour/pattern you can imagine. I got 3 for £10 including postage. They are really good-slightly bigger than shop bought ones but just as absorbent.
If you look up dribble bibs on there it should bring loads up.