Guy at best buy told me 128 was the highest it went, when I asked about their stock. They just want a sell. He tried to say there was no such thing as 256 or 512 versions. Very confidently.
I don't expect the short-timers (clerks and salespeople on the floor have extremely high turnover, so training on all product is very hit and miss) at places like Best Buy to really know much about the Surface lines. An MS store, I expect, would be much better, but this is no help to a lot of folks overseas.
It will only get worse during the holiday crunch, at least in the U.S., when retailers hire a lot more temporary seasonal workers to fill the sales floors for additional shifts. These people get minimal training as well and probably aren't so interested that they will do their own homework; remember, these are the same people who are blamed for at least part of the confusion between Windows RT and Windows 8 last year during the holiday purchasing blitz.