I've got a general tip for purchasing software, and it's a valid approach for any website that allows you to pay in the currency of your choice.
 
Right now, the Euro is weak against the dollar (relative to its position over the 5 to 10 years). 
 
Some websites (such as Time and Space .com) allow you to pay in any currency you want.  Often when they have sales, they've adjusted it correctly for one currency, but one of the other currencies is significantly better to use.  I think some of these good deals come also because they adjust the prices to include VAT.
 
Here's a specific example:
http://www.timespace.com/product/OMNI-1/6/spectrasonics/spectrasonics_omnisphere.html
 
Spectrasonics' Omnishpere--Assuming you're in the U.S., you don't pay VAT, so you get the lower price.
 
Here are the current prices without VAT:
In dollars, $498.
In pounds, 232.51 which is roughly $349.
In Euro, 298.71, which is roughly $336.
 
Shipping to the U.S. is roughly 14 Euro, so by  paying in Euro, you can get Omnishpere shipped to the U.S. for roughly $355.
 
I have not *personally* done this deal, but I have used this strategy before especially at timespace.com.  Sometimes pounds are the cheapest, sometimes dollars, and sometimes Euro.  Check all three and use xe.com to see the exchange rates.  Click on the items, because in the search results they include VAT.
 
Not only that, timespace.com occasionally sends customers coupons which can be applied nearly storewide (excludes VSL for instance).  So, this Christmas, I got Impact Soundworks Celestia.  It was on sale for $99 on the site, but paying in Euro's it was $84.  I added a 20% off coupon and scored it for roughly $68.
 
Just a tip to help you save some dough!
 
 

I tried this, but it looks like Time+Space will not ship Omnisphere to the US, my order was cancelled.
 
Hope this helps.

Yeah, that's what I hear.
 
That being said, my overall point is a good way to get deals.  Watch for the currency conversion differences at Time & Space.  As I noted in my other example (Celestia by Impact Soundworks), you can definitely get good deals this way.  Perhaps it's best to use the strategy on downloads.

I bought the New York Drums Preset Bundle for Superior Drummer today
from T&S and didn't even notice that I was paying in Pounds.  It was supposed to be
$32.50 US with no VAT.  But when I checked it it ended up being $29.70....so that
made my day! 

  Most vendors don't have it in stock and it has to be shipped to them. This one of the few products left that are not distributed digitally.  I don't expect there will be a sale on it from vendors trying to clear out their physical stock.   

cclarry
I bought the New York Drums Preset Bundle for Superior Drummer today
from T&S and didn't even notice that I was paying in Pounds.  It was supposed to be
$32.50 US with no VAT.  But when I checked it it ended up being $29.70....so that
made my day! 

 
If you would've paid in Euros, the cost would've been even cheaper:  $27.58 (after conversion)
 
*ALWAYS* check all 3 currencies! ;)