I bought a rubber "universal" boot liner from Halfords for about £20 a year ago - wasn't aware of the OEM ones, just wanted some protection for the boot.
Just found it online:
http://www.halfords.com/webapp/wcs/s...egoryId_165494
Gone up in price unfortunately, but after trimming, it fits great, looks good, is hard-wearing, doesn't move around, and is ideal for the purpose.