I recommend using
ebookprice.info to find ebooks. It does not search the Sony store, but it does find both US and UK ePubs. In this case, Waterstone's in the UK has an ePub of Rabbit Run and many John Updike titles are available in the UK as ebooks. However, I suggest going to
WHSmith instead. They sell world-wide and don't charge VAT if you live in the US.