Considering the AusRegistry wholesale price is $20.35 and the auDA domain fee is $3.85 anything around $25 doesnt leave much room for support. (source)
I think $35 is a good price or anything below (i.e sale price) from an auDA accredited registrar as there are minimum requirements for levels of support.
Also as Wade pointed out here if your going to be buying names in bulk its always beneficial to talk to your registrar..