Yeah, same here. Hadn't pre-ordered but when they arrived, and I saw how nice they looked, I managed to pick up the ones I wanted easily enough, discounted from my usual retailer. I did end up paying full RRP for one coach from Hornby themselves many months later when I decided I wanted an additional one.
Might be different with the Observation Car but, given Hornby have done a second run of the Coronation Scot and the APT, I wouldn't be surprised if they do the same with the LNER Coronation rake if it sells out relatively quickly.