I have the Japanese book and basically learned that I will never have a satsuki of that caliber because of my climate. All good ones are grown in a long growing season in the ground. Once the size is achieved then they can handle all sorts of abuse according to that book. I have 3 little shrubs. It is still fascinating and the book is worth it just for the photos of all the beautiful azaleas alone imo!
Kale, you don't have to have the perfect climate to grow your own, do like I just did. Stop buying cheap nursery stock every month, instead set the money aside. Make one significant purchase a year. There were only 3 digits in front of the decimal point for the 'Shin Nikko' that I bought. It was just under a thousand usd. The tree itself was originally imported from Japan a decade or more ago. It had been in the collection of Bob Gould, who due to advanced age (he's in his 90's) had asked Rick Garcia to sell a few of his satsuki. The tree has a few minor issues, but at superficial glance you can't see anything obviously wrong.
You can actually see half of this tree in the lower left photo on page 12 of Rick Garcia's new book. When you consider the time Bob Gould and various professionals have put into this tree over the 40 or 60 years of its age, the price I got it for was quite reasonable.
It is "kinda neat" having a tree that appears in the latest book on Satsuki. Even though it is just a background tree, with only half the tree showing, the other half was cropped. It was not the focal point of the photo.
Point is, you can skip the "nurseryman phase" of bonsai for less than the price of a 10 year old automobile. Stop buying dozens of cheap trees, save up, and once a year, make a significant purchase, one that enhances your collection.
Not trying to bust your chops. When I first started, I was afraid to buy anything expensive, because I was afraid I would kill it. It took a few years, 5 or more years to gain confidence. Then I got cocky. Then I killed a really expensive tree. Now, I am more humble, and it forces me to not be casual about my horticulture. Think before cutting. And don't put off the necessary. Yes, go out and water even if it is too hot to step outside. Especially if it is too hot to step outside. And staying on top of pest infestations, if you see bugs, kill bugs. Don't let them get out of control.
I don't have many trees, 5 or so that I could possibly bring to a club show. This one makes 6, I have maybe 50 cheap things either from nurseries or that I dug for free from the farm. Key is, don't let the cheap stuff distract you from focusing on your "good trees". Too many sticks in pots and you won't have time to create bonsai. You will just be watering sticks in pots. For the last 5 or 10 years, I quit with the nursery crawls. No more new nursery stock. I keep my ear out for intermediate to advance trees coming up for sale from older members of the club that are downsizing their collections or I talk with visiting artist like Rick Garcia, or Ted Mattson, or any of the travelling teachers. There are a handful a real bonsai stores, like Hidden Gardens in Willowbrook IL, that broker trees. And like I suggested, these trees have work in them, so they are not cheap, but you are saving years or even decades of work by spending the money.
So if you are lucky enough that you can afford to do it, pry open that check book, and buy a tree that is more than a couple car payments. You will save years of work.