the ONLY way you can find a full suspension bicycle that you can actually ride for $300 is if it is stolen and the person selling it need money for crack. i'm not trying to be a jerk, i am trying to help you. potholes in the road don't mean you need full suspension. paris roubaix is done without full suspension (not at all comfortable, but it *can* be done). chances are you don't need it. if you HAVE GOT TO have full suspension, you are starting at over $1000 for just the frame.
"..... hopefully with at least full disk brakes, shimano gears, dual/full suspension, at least a 19" frame, and weighing less than 35 lbs."
again, i'm not trying to be a jerk here, but that is completely unreasonable.