Just got an iPhone 4! I've searched and read many threads, but few describe how their armbands respond to sweat. I currently have one for my old phone and it kept slipping down my arm when I'd sweat. I'm just looking for something cheap/reasonable, not a $50 armband. Pretty important to me though since I use it 6 days a week. Hopefully the Ronnie Colemans of macrumors can help me out here.