I'd go for the Andis AGC Super speed clipper. Exactly the same as the Andis two speed but with a more powerful motor for just a couple of pounds extra.
http://www.groomers-online.com/product.php/308/andis-agc-super-speed-clipperWe have both and the Super speed is just brilliant for ploughing through Milly's really dense coat but is just as quiet as the standard 2 speed while, at the lower speed, it's extremely quiet and great for any fiddley bits and around the head, ears etc.
The one you've posted is £76 plus £15 postage so you're over £90 already, an extra £40 would, in my opinion, be well worth it to get what's arguably one of the best cocker clippers out there.
Bob.