I have some friends that bought a pre-made one, and personally..with a price tag of $270, I'd make my own too. lol, Heck the wood, hammer and nails would cost less than $50 at Home Depot.
But anyhow..I LOVE theirs. They live in a condo at the beach and only have a balcony, and dogs are restricted on the beach during tourist season. I think they bought theirs from someone here in town that makes them and sells them at the flea market? It is a wooden box, with a place cut out to go in and out, and they use real grass, which has to be replaced every 3 months (I think she said) But she took some wallpaper trim (or whatever its called, border..I think?) and she put that on the outside of the box, so its really quite pretty. The dogs use it religiously.
So, though I don't have one, I'd surely get one if we didnt' have grass closeby. And you can always paint them, or use the border to make them all pretty
I'd probably go with real grass, too. Since Havs poop is so tiny, Gucci's seems to disentegrate into the grass quickly.