https://www.bowwowflix.com/ Heck of alot cheaper to rent, then buy... dude thinks quite highly of a couple hours of him playing with dogs.
Not that I begrudge him, he's got the pedigree to charge what he wants. But having watched him and Michael Ellis, I'll say if I was going to buy one outright it'd be Ellis's stuff. His require multiple rewatches just to pick up on all the intricate knowledge he's sharing.
Don't take that the wrong way though, Ivan is a winner plain and simple and his methods obviously work, are clearly illustrated, concise, and aren't filled with overly complex explanations. They're great DVD's, just saying you could watch once, take good notes, and get a visual refresher for free on youtube.