When you're after a fast memory card, it's a real minefield out there. Manufacturers quote speeds that are rarely realised in practise, or they just give vague read speeds without a write speed. So with this one, the vendor has kindly included some benchmarks.
The write speed is most important for me, so I bought a 16GB one to use in my DSLR. With my laptop's inbuilt card reader I get 40MB/s read and 30 MB/s write for large sequential files, but according to benchmarks on the page, you should get 80MB/s read and 40MB/s write with a USB 3.0 adapter.
Comes in bulk packaging, but with an SD adapter.
There's a 16GB version for £7.99 as well, but you'll need an add-on item to get to £10 for free postage:http://www.amazon.co.uk/gp/product/B00K7Y0FOU/
Both sold by Sunwood-UK and Fulfilled by Amazon.