Thanks everyone for all the posts, looks like plastic is the way to
go, but I was asking about best value - Im on a budget of about $2000.
Want to get the biggest tanks I can get delivered for that. No pump, I
live on a slope so will gravity feed driplines.

Dynaplas seem to have a store on ebay!
delivery syd is only $95

looking at this
http://cgi.ebay.com.au/4350L-RAIN-WA...2.m153.l1 262
They seem to be joining 3 tanks via polypipe to make up 4350l of
storage. Splitting storage into 3 tanks must be easier to
install and handle but wondering if there is a disadvantage.

sellers store http://stores.ebay.com.au/yourippa-Truck-4wd-car-van

thanks
George