This one is the cheapest and also with free postage,

http://www.ebay.com.au/itm/Fipronil-Granular-Ant-Killer-Insecticide-Poison-500g-Non-Repellent-Professional-/142092910507?hash=item211565bfab:g:j~AAAOSwU-pXuTG2

Cheers,
BB.

I live a 24 Hour lifestyle, but every now and again I seem to fall asleep, well at least that's what my wife tells me.