https://www.buybackyardbuddy.com/
That I think is the cheapest I have seen one. I have seen them for 120-200.
Do you want to have in potty trained in the grass? is that why you want one of these? I wanted to get one too, but then I was like its like having a litter box to clean..then I thought to myself how am I going to lug that around to clean it...I would think it would smell more too!!
DH and I live in a condo and I didnt want to set it on the patio bc I dont want Peanut to go out and potty when we are not home to watch him...so to me it seems like more hassel than what it is worth.
But if you are wanting to train him to go in the grass I think it would be great.
Will he be able to go out and use it when no one is home to watch him? Just make sure he has NO way to fall off the patio, you also have to think of things being able to get him when he is on the patio..I doubt it, but you never know! I just try to think of everything that could go wrong and prevent it