Yeah I experimented with binder clips also. Sometimes the cards in the middle slide out of the clip and the whole thing falls apart in your pocket. Rubber bands are more secure.

Binder clips might work better for holding paper money (ie, a money clip). But I use a rubber band for that also.

When you stick everything in your pocket, put the credit cards toward your leg, and the paper money on top (away from your body). That way, if you work up a sweat running for your plane, your paper money stays dry.