And they probably never will gait if they are trotting without a great deal of work. These are horses that you either gait (it is natural to them) or just trot.
Trotting is much easier for a gaited horse and if they are taught to trot they don't want to gait. Gaiting is built up by muscles and the way they use them. I know I had a "trotty" KMSHA and stupidly thought I could retrain her. Didn't work.
The horses look to be well taken care of. Just beware when a breeder starts throwing out the fact that "my stallion traces back to Old Tobe". Heck they pretty much all do. Rockies are still fairly rare and should be bred for intelligence, gait, willing attitude and love of people. Most babies gait from the get go. We have a 7 month old that hasn't moved in anything but a gait when he speeds up. He is as sweet as the day is long, very laid back, and takes everything in stride. That is what you look for. There are a couple of bloodlines to watch out for that have a pretty "hot" stallion I wish I could remember his name. A lot of his "get" are wonderful one day and an absolute idiot the next.
Also watch out for possible ASD in babies. This has happened from too much inbreeding with chocolates for that perfect color. Just google Rocky Mountain horses with ASD for the particulars on it. And for a good well broke animal be prepared to pay at least $2000. You can pick up babies fairly cheap, and I have seen people work with them as 2 year olds establishing ground work and by the time they are 4 they are on trails.
What she said...minus the ASD part...ASD isnt anything to be concerned about, it doesnt affect the horse in anyway other then the crazy eyes, no harm, no pain. We do not however breed for ASD. ASD is caused when two chocolate horses are bred together and a double silver dapple gene is conceived, not really any inbreeding or close breeding. Several years ago when I was younger ASD was a sin, and you couldnt give a horse with it away. That's when 'Pence's Blue Boy' was sold for practically nothing and now he is one of the most sought after horses to breed to for a high stepping horse, with little to no conformation at all. Now, people want to breed to an ASD horse, b/c you will get a Chocolate horse, or a Red Chocolate (Silver Bay), b/c it will have 1 copy of the Silver Dapple Gene from the parent with ASD (Double Silver Dapple). Some people get lucky, our Storm Warning Grandson was bred to two chocolate horses, and shows no signs of ASD, but had a snow white mane and tail, that happens some...not often.
If your looking at a younger horse. Im going to say 6 or less, look at the lines. Sam Clemon's Tim (Tim) is one of the 5 Sons of Tobe, and is known to have a hot babies, so even if Tim is a grand or great-grand sire, the foal can still develop a hot streak, and be moody. As far as breeding stallions of today, Doc Holiday, Blue Smokin' Sambo, they throw hot babies, it even comes down to an art of detecting them. I can pick out a Doc Holiday foal b/c they will turn their butts to you and show signs of being kicky. French's Stormy (sire of one of our studs and Storm Warning) throws a lot of Trotty Horses, this is seen in Storm Warning foals as well. Nothing wrong with it, once they find their gait, they lock in and they are gone, and stick to it untill they die. Personally I like Nuncio, I havnt found a Nuncio horse I don't like (we have a 55% Tobe Stud out of him) and I also like Sewell's Sam (out of Tobe), sam was the first horse to have a White Mane and Tail, and his foals usually show it without being ASD or his grand foals show it without being ASD.
But find something you like, and you can handle. I look at buying a horse like buying a truck. If your going to spend that kind of money, get exactly what you want and get something that you can handle, don't just settle for the first thing you see, trust me there are plenty of horses out their.