Getting the same "authorization declined" error message as reported above, using a US Visa card and US delivery address. Damn. Thought I had it!
After my transaction was denied, I received an email from my bank about the overseas transaction. Turns out the fraud dept. had stopped it. I authorized it, and they had me go back to Cleverboxes site and repeat the transaction. This time, it went through!
I have a confirmation number in my email and the bank lady told me the transaction went through, so I guess we'll see if Cleverboxes delivers. The website is still showing around 100 in stock as of right now. Shipping cost to MA, US is something like 50 pounds.
Total cost was 209 pounds, or about $342.
I wouldn't be surprised to get a cancellation email from them tomorrow, because it clearly says UK CUSTOMERS ONLY, but whatever. I'm trying what I can.