Hi, Dragonsong.
To date, Warner Bros. has NOT released KF:TLC on DVD; neither by season or especially by boxed set of the entire series. So anything you'd buy on that website is a bootleg. There have been some instances that I've heard of where the DVD's are listed as "region free"; hinting that they were home made copies; if they advertise them as DVD +/- format - definitely the sign of home made stuff. Some of the stories I've heard of places like this have has people getting the DVD's and the commercials are still in the shows; they were literally just recorded of the TV broadcast. If you're intent to buy them from this site, I'd seriously question them about the quality of what they're distributing - find out what generation they are; after the orignal broadcast, a lot of the episodes have had material cut out of them to allow for longer commercial breaks, so you may have scenes missing.
Something else to consider is where they're shipped from. I've been given to understand that a lot of these entire series boxed sets are created in China at very low cost, then drop shipped to other countries (Canada for instance) and then delivered to customers from there, making it seem that they are products of Canada.
Another thing to think of this: if you buy these bootlegs, nobody affiliated with the show gets any residuals. So you're basically cutting into their potential income and ripping off more than just the studio.
Finally, I'd find out what kind of customer service they offer - will they allow returns or exchanges or even refund you money if you're not satisfied? Buyer beware and all that.
Just mentioning a few things, is all.