OCUK are doing some gouging yes - don't like it, shop elsewhere. However, the prices are generally high everywhere because of the exchange rate.
When the 900 series released GBP/USD was 1.6. Now it is ~1.3 so there is a 20%+ increase in prices (compared to the launch prices of the last gen) just from that.
That is the unfortunate reality of the situation.
Also, that link you posted of the American price looks like a special offer/deal. We have had those here for the 1000 series as well on some this week only or day offers. Elsewhere on a another popular American retailer that card is listed as $709.00
sigh... the price is NOT to do with the exchange rate. (certainly not mostly) or else how could it possibly be less dollars than it is pounds. think about it.
That isnt a special offer. It's right across the range. Every card is less dollars than it is in pounds here.