I needed the samething, until I came up with something to use in the meantime. I took a rectangled laundry basket, turned it upside down and covered it with a bath mat. You know the ones with the rubber back? That's kind of mat/rug I used to cover my 'step' aka laundry basket..hahahah..it works like a charm. It's cheap and doesn't take up too much room
All 12 of mine use it at night when they have to go, they jump down and go on the pee pad and then come back up without disturbing me. It's great!
Good luck!