Love this stuff and I've never seen it so cheap. (Thanks tantryl for spotting) Apparently BWS is having 30% for any six wines which includes the Grandfather Port. http://www.bws.com.au/winespecials.html but I can't confirm if it applies to Port.
Went to Vintage Cellars to see if they could match it, as they have the single bottles for $96, Noticed that there is a possible price error with the 2 Glass combo pack for $84.43. Which the guy then took down to $82.99
Pay with ING Direct paywave made it $78.84! (5% paywave rebate)
Boozle are showing these at $66.49 each if you buy a half dozen at BWS & Woolies.