I know when I run I'm even worse than you because without my armband I'm carrying my iPhone in one hand and my keys in the other. Cheapest option I saw was $15 for other armbands.
I think you can use Griffin adidas miCoach Armband. Its great to use and its price is very reasonable, That is only for $15. Also you can use Belkin DualFit Armband, its price is $15 too.
I know when I run I'm even worse than you because without my armband I'm carrying my iPhone in one hand and my keys in the other. Cheapest option I saw was $15 for other armbands.