I'm not sure that this item is the same thing you are looking for but it does say its a step in harness. I'm considering getting one of these myself and the price starts at 4.95 at jefferspet.
http://www.jefferspet.com/ssc/produc...9WMNRGTR4GA5E8
Sorry the above link didnt take me to the correct item.
Just type step in harness in the search and it should come up.