what exactly do you want to buy from the UK? One local aquatic centres I use will ship to the US. However, it really does depend on what you want You could well be paying a lot more for postage than the actual item costs.
Check south Devon aquatic centre out, you can contact them via the website, they are very friendly. You can ask for Andy or Wes. Also tell them that you came from here, looks good for me since I did website for them:lol: it's not actually their main website, it is one I did for a favour
http://www.southdevonaquaticcentre.oscarfishlover.com/