Do you want the Cannondale frame, or have a use for it?
I'm pretty sure the Trek frame is worth a good bit more than the Cannondale, especially in that tiny size. I had a 1981 710 frame in excellent condition and got a repainted Eddy Merckx out of it... I think $200 is a fair price for the frameset. Of course it depends how good of a friend this is and what kind of deal you're willing to give her.
If it was me, dealing with a random person I didn't know/care about, I would want $200 for the Trek frameset or the Cannondale frameset and $100.