Just noticed that Seagate are shipping their 8TB external in a few days. $299 on Amazon in the USA. Not bad at all if you are looking for some serious storage space on a single disk.
http://www.amazon.com/Seagate-Deskt...TF8&qid=1421092999&sr=8-3&keywords=8tb+drives
http://www.amazon.com/Seagate-Deskt...TF8&qid=1421092999&sr=8-3&keywords=8tb+drives