Nong
You are correct it doesn't say anything about 250' for RA, I was wrong on that point and happy to admit it. But if you take a look at the link below it will outline what can be done. You do need to have a low level endorsement (or permission from RA-Aus) and you do need to comply with CAO 95.55 (aeroplanes) and CAO 95.32 (Powered chutes and Weight shift).
I don't necessarily agree with all the rules that are applied to flying but if we don't comply with those rules we will eventually we will not be able to fly or it will become so regulated that it won't be worth it, additionally the rules are there to enhance safety and that's not a bad thing.
http://old.raa.asn.au/opsmanual/2-01.pdf
From CAO 95.32
8 Provisions relating to flight height limitations
8.1 An aeroplane, to which this Order applies, may be flown at a height of less
than 500 feet above ground level, or 300 feet in the case of a powered
parachute, if:
(a) the aeroplane is flying in the course of actually taking off or landing; or
(b) the aeroplane is flying over land that is owned by, or under the control of,
the pilot; or
© the owner or occupier (including the Crown) of the land, or an agent or
employee of the owner or occupier, has given permission for the flight to
take place at such a height; or
(d) the pilot of the aeroplane is engaged in flying training and the aeroplane
is flying over a part of a flying training area over which CASA has, under
subregulation 141 (1) of CAR 1988, authorised low flying.