I’ll offer a different opinion, that statement is hogwash. (Where does that saying come from anyway???) If the sound that moves and inspires someone to play, is that of the low whistle, rather than it’s high pitched, twiddly, and oftimes irritating little brethren, then there’s no reason why one shouldn’t start on the Low D.
Sure it’s going to be more difficult to finger a Low D than a High D whistle, but even so, the fact is that, when compared with other instruments one could learn to play, the Low D is still one of the easiest instruments for a beginner to start on: Bar chords, most of the 4 finger chords, and many scale patterns on guitar will give people far more difficulty than playing a Low D. Learning to play the single most “common” 4 finger chord on mandolin will cause far more discomfort than learning to cover the holes on a Low D, and many people routinely start out on the D flute, which is certainly more difficult than Low D, by at least a factor of 5. And lets not even talk about learning to play something like the fiddle 
In my opinion, this idea that the Low D is so much more difficult than the Soprano D comes largely from those who have started on soprano whistles. Sure, if you come from that angle, the big whistle is going to seem a challenge, however if one starts on the big whistle, with no preconceived ideas or habits, then it’s really not so difficult at all. That’s how I started, and I don’t recall it being terribly difficult, even though I have fairly small hands.
Also, Let’s not forget that a huge part of the motivation to play (and practice) comes from enjoying the sound we produce during those activities (although I’m still not sure anyone enjoys the sounds I produce), so it makes far more sense for someone to struggle a bit with an instrument they really want to play, rather than toil away on something else, that may be a tiny bit “easier”, but doesn’t produce a particularly satisfying sound - yes, believe it or not, high whistles just don’t do it for some folks, imagine that.
DJK, I’m sorry I can’t answer your question about the particular whistle you mention, as I have never run across one. Don’t let folks here discorage you from starting on the Low D, if that’s really what you want to play. A couple of Low D’s that are decent, and perhaps in your price range are the Howard Low D and the Tony Dixon Low D. The Dixon is particularly easy to play, if not the most resonant. The Howard has better tone, but is a bit more challenging both breath and fingering wise, but it’s still fairly easy to play. Both offer good bang for the buck, and both can be purchased on-line. Eventually, see if you can find a good used Goldie Overton, when your budget allows.
Good luck with your search, and have fun with whatever you end up with.
Loren