If you're reasonably handy with photoshop/elements I think you can get better/as good results with taking 2 (or more) exposures of the same scene. Camera has to be mounted on a tripod and dead still for this though so both pictures are exactly the same (apart from the exposure*). Then blending the two after using a photoshop version of a graduated filter. Doing it that way allows you to set the shape/boundary of the gradation (rather than having it straight across) to follow your horizon/scene and not make for instance, tall trees look unnaturally dark where they project into the shaded top part of the filter.
*in one shot the sky will look ok and the foreground dark, in the other the foreground wil llook ok and the sky will be very white or blown out.