Turbopower 1000's aren't that rare at all.
Turbomasters are more so, but it depends on the model. The softbag one's are quite rare, the exclusives are like gold dust.
You have to bear in mind that Hoover were a HUGE seller for many years, so the main lineup models aren't that rare at all, with the exception of the U2336 Turbopower. Despite being a big seller, it was made of incredibly brittle plastics that were prone to splitting and shattering, so not many survived. The store and catalogue exclusives are the rarest models. For example, there was a pale blue Turbopower in the early 90's that was an exclusive to Argos and an all black model exclusive to Littlewoods. I don't think any of the UK collectors have examples of those.
I'd say the most rare overall are the Concept 1's and the later Convertible uprights (Dial A Matic in the US) . They're very hard to find over here now. Some of the top end Sensotronic's, Freedom's and Compacts are also quite hard to come by too, especially the ones with the powerheads - they were very expensive so didn't sell in such huge numbers as the cheaper models.
[this post was last edited: 5/17/2015-11:49]