In NSW - We've been on the M7 and M5 twice (return trips) this year without any electronic gizmo and just paying later, but I suspect we're getting ripped off (admin fees etc) doing it this way so we'd like to buy one which is best suited for someone using these toll roads maybe 2-3 times a year.
I've done some research and only gotten more confused.
Please help :)
http://www.myetoll.com.au/
$40 security deposit for up to 3 tags, no ongoing fees.
Convenient to obtain and return.