Meritline has the Mini Microphone Recorder (Black) for Apple iPod / iPhone 3GS / iPad for $2.49 - $1.60 off with coupon code MLC262457072964AL1 [1000 uses] = $0.89 with free shipping. Adds audio recording ability to your iPod Nano, Classic, or Touch.
Excuse my ignorance, but one needs this for the iPhone why? Is there any reason why the on-board mic isn't good enough?
Listed as ipod first from seller. This is just Ben's description.
pretty cheap