I think the Cybook's probably the simplest option and is a decent book reader - possibly not quite as good a "feel" as the Sony, but better font handling capabilities. It supports the Mobi format, rather than the Sony's ePub/LRF/LRX, so there's probably more titles available for it than the Sony.
Here in the UK, WHSmith might be the easiest option - I don't know if they stock them in the stores, but they have it
on-line.
Note that with the Sony, the font size is variable Small/Med/Large but the base font size is set on a per book basis, so what you saw need not be the final answer - if it's unDRMmed you could tweak it yourself - but a Cybook would be simpler & quicker.
See at time 3:13 on the video
here