Thought I'd start the ball rolling with this - cheap homebrew stuff in Sydney.
For hops and grain I've found ESB in Peakhurst to be the cheapest.
http://www.esbeer.com.au
Grain - $3.50 a kilo (cracked), or $29 for 12.5kg, and $45 for 25kg.
Hops - $9 for 100g, $36 for 500g, and $61 for a kg.
Anyone else got any baa-a-aaargains ?