Buying from the US - USD to GBP?

basically I'm buying a new bmx from an American site with the currency USD, now what i want to know is will it be changed to GBP along the way, the item cost's $799 all together will that be changed to �494? instead of changing $799 to �799 Ive never done this before so thanks for any info, here is the exact item http://www.danscomp.com/101147.php?cat=BIKES