where can i find dvd's of the george lopez show besides season 1 & 2 i have those. are there anymore out?

I don't think they have any more dvd's of the show besides season 1 and 3 because it came out on dvd in 2007, right around the time the show was coming to a end. I know this because I was looking for it too, but the only way to get more dvds of the show is if you copy them.