Try going to a professional framers where they have lots of frame and matt samples. We do this every time now and have a great framer who just sits and experiments with us for ages - I think he enjoys it even more than us and he has a fantastic eye for picking out colors and styles we never would have thought of. It's more expensive than getting a ready made but it makes such a difference to the finished look - even cheap $10 prints can come out looking amazing with the right matt and frame.