Look at the XtremeTurbine 120mm case fans. They're not the cheapest, at $18 apiece... But they're 90cfm at 32dbA. May not be the quietest for 90cfm, but the biggest advantage they hold is the static pressure. Because they've got 16 blades that are relatively close together, they are able to push high cfm over more restrictions (perfect for your radiator). Here's a link and pic, you may be able to find them cheaper than this, though.