Looks to me like it would possibly cost more to get in the UK. Suppose it depends on that price including VAT or not but if it doesnt then its going to be half as much again even if the UK grabs you for customs charges
$280 plus 20% = $338 plus post, if it does already include VAT then not so bad.
If I recall the ESS is $195 then you will possibly have customs charge of £10 ($16) plus VAT so total before post would be $253. Post from the USA shouldnt be that expensive. Thats the worst case from the USA, sometimes you get lucky and things sail through without customs so that would be $195 plus post.
One drawback to getting from the USA is the time of year, likely there will be a slow down due to Christmas post so it may take a while to arrive rather than the normal few days.
Hood