There's nothing more frustrating than seeing that when you're itching to take advantage of the cheap dollar and have finally found the perfect dress/shoes/whatever. There are ways around it though.
I've decided to write this as I'm aware that I feature a lot of shoes on US sites and it can be very frustrating to learn that in the age of a global economy, The Rest Of The World doesn't seem to matter or exist.
Option 1 - eBay.com
The US eBay site should be your first stop when looking for stuff you just can't get here. Not only is it likely you'll save on the retail price anyway, the current dollar position means that's even more favourable. Most sellers will ship internationally if you ask them should they not already state they do. As a rule, should be between $11 to $30 depending on the item and the method of shipping. That's still only around £5 to £15 which is pretty good going. For example, I recently won a BCBG Max Azria dress which cost £26 including shipping. RRP? $380 or around £195.
Option 2 - get a US postal address
This is fairly straightforward yet remains something that people just don't seem to know about. I have my US address with Access USA. Most places offer a month by month subscription or a yearly subscription. If you can team up with some people, share the cost of a yearly subscription and shop en masse. They also offer personal shopper services for sites which don't accept international credit cards. Obviously there is a charge for this but even so still works out cheaper than buying here. I use it to raid Sephora and save around a third on all products - great given that I love Benefit and Clinique!
Most sites will accept international cards if you can provide them with ID. Yes, it's a bit of a hassle but worth it in the end.
Option 3 - There are US sites that ship internationally!
You just have to find them! Threadless, Delia's and Pin Up Girl are my personal favourites but the number is growing. Bookmark all your favourite sites and keep checking to see if they've changed their shipping policy. I've found that many that I've emailed have replied saying that they will be doing international shipping "soon" - whenever that may be!
Legal time - be aware that anything that gets shipped to you from anywhere abroad is subject to Customs charges which can be a complete headache to understand. It's always worth factoring this element in to any shopping you do. For proper info on this, head to the HMRC site which gives a good explanation once you've got your head round it!