Disney CMF are sold out in most places already (including S@H). Lots of non-AFOLs buy them. It's going to be the same with the Castle, regardless of it's price, unless they fail in design. If it's long enough on the shelves, like Death Star was, most people who are already into an expensive hobby can easily save money for it. And many others will buy it simply because they care for Disney.
It's going to be huge and opened on one side, or smaller but more GB HQ-like. Hopefully it'll be both!