Yes, both IrisVR and Vectorworks Designer offer a Free Trial.
IrisVR is designed for Large Enterprises, Medium Business and Small Business.
Vectorworks Designer is designed for and undefined.
Pricing for IrisVR Starts at $225/Month whereas for Vectorworks Designer Starts at $4,813.
Some top alternatives to IrisVR includes BIMx, BIM Track, Vectorworks Architect, Vectorworks Landmark, Archicad, Revit LT, Vectorworks Designer, SENTIO VR, Enscape and bimU.io.
Some top alternatives to Vectorworks Designer includes YouBIM, Space Designer 3D, Vectorworks Architect, Vectorworks Landmark, Navisworks, Archicad, Revit LT, IrisVR, MasterSeries and Autodesk Design Review.