Pure ASH tone is actually blue. You can get it from a professional hairdressing supplier.
It very strong so you have to use it quite carefully.
The following are the names of wash-in, wash-out products that really work:
RedOut
The effects last a few weeks. It can be messy to work with.
Best to dip your comb in some and apply it that way to avoid contact with the base.

L'Oreal also do a similar product in their Expert Series called Silver Gloss Protect System.
I bought this last one whilst visiting Australia, so you shouldn't have a problem getting it.
Here it is:
http://www.ebay.com.au/itm/Loreal-Silver...1c20f98caa


Here's another product available on Australia ebay:
http://www.ebay.com.au/itm/Manic-Panic-V...43aad918df
or:
http://www.ebay.com.au/itm/Paul-Mitchell...4cf95183ef
or:
http://www.ebay.com.au/itm/Farouk-Organi...1c20f80af1
or:
http://www.ebay.com.au/itm/TRESSA-LITEWO...4cfae145d4