The bad news is Acar sketches aren't worth as much as they once were.
The good news is this is an earlier one and will be perceived as being of a better quality than some of her recent packed out efforts.
Personally, I wouldn't take less than $200 for it.
My sketch collection: http://sketchcollectors.com/gallery.php?user_id=727
I'm offloading my sports cards for cheap. Check out MonkeyLots in a B/S/T forum near you!