Where can I buy a USB Byte Blaster II download cable from?

See the download cables (https://www.altera.com/products/boards_and_kits/download-cables.html) page for details of what's available.

There is also the Terasic USB Blaster Cable:

Or the compatible ee blaster (http://entner-electronics.com/tl/index.php/eeblaster.html), which will probably be cheaper to get if you are in Europe.

If not mistaken, I heard that USB Blaster will no longer be selling. Thus you might want to consider getting USB Blaster II cable.

Hi, I think I saw this USB-Blaster II sold at digikey.com. and maybe you can check the price from Altera's sales/distributors too

Here is a link to their worldwide sales office:

go to the Altera site then get go to contact us, find the nearest sales office and contact them directly, in case you need to ask for more details. :D