well sears sells individual ones and id imagine home depot or lowes also carries them and can't forget your local hardware stores either. dremels can be purchased in a number of places as well from walmart to target to home improvement and hardware stores. Even harbor freight if you have one near you as they are not the dremel brand but a cheaper equivalent.
if all you have is smaller screw drivers, id also invest in larger flat head and phillips head screw drivers. Using a smaller flat head may be the reason its stripping out and why it won't turn out.
