If you go to the Stab racing site: http://www.tab.com.au/Racing/Default.aspx?State=1
and click on a race, then click on bet type Quin, one of the option boxes you can then tick is 'Roving Banker'.

You don't need money in an account to do the above [only if you wanted to process the bet].

I bought one today at the local TAB [Vic] for the first time and on the ticket it said:
.......RACE 3.........
QIN 6RB,1,4,10,11

No. 6 [Roving Banker] can come either 1st or 2nd and if 1 of the other 4 horses gets up in 1st or 2nd place with it its a winning ticket. 1 unit cost me $6.

Now, apparently in NSW [Unitab] they have the same type of Quin called a 'Banker Quin'. The banker can come either 1st or 2nd with another one of your runners. Identical to the Roving Banker Quin. However the cost is only $4 for 1 unit. Why?