Hop on over to Amazon where they are offering this highly-rated Shepherd Hardware Heavy Duty Rubber Door Wedge in Brown for just $2.74!

This heavy-duty door stopper is made with durable rubber construction and features an anti-skid base to safely wedge doors with up to 1-1/2? of floor clearance without scratching or denting hardwood and laminate floors. It can be used in all environments including industrial and commercial.