On the other hand, EnergyPlus and all Open Studio plugins are completely free, but in my experience can become really time consuming if you're using them separately.. for example OS just for modeling and E+ for simulation runs! A new GUI for E+ is expected this year by DOE, so you can check it out here:
http://simulationresearch.lbl.gov/projects/gui We'll just have o wait and see..
P.S. Also, check out gModeller, a Green Space plugin for Sketchup. Modeling-vise only, it can be a piece of cake, so that later on you can use those models in E+ via Open Studio.