All ultrabooks have to have some sort of flash, either a full blown SSD or a flash cache. Manufacturers are milking the idea of a price differential.
750GB 7200rpm drive will cost me £75
128GB SSD will cost me £90
256GB SSD will cost me £150
With the 750GB drive the manufacturer has to also include a small amount of flash to act as a cache. This means that a 128GB drive costs about the same and the 256GB drive is only £60 more. SSDs aren't a high end option any more they are simply a choice between speed and storage space.
The Sony Vaio Z is a prime example of this, if you want 8GB of RAM you have to get the 256GB SSD (I'm guessing Sony's Windows install is so bloated that the extra page file used for 8GB RAM consumes all the remaining space on a 128GB drive). The 256GB drive is an extra £400 on top of the 128GB.