That's why WASCC Tuning days are awesome, heaps of track time, so really good bang for your buck. They tend to alternate tin-tops and open-wheelers in 20-30min sessions. With your WASCC Membership you get a free Tuning Day (Normal cost about $75), so helps offset the cost.
WASCC Membership is annual, but membership is now being charged on a pro-rata basis, so you only pay a reduced amount till the end of the year
www.wascc.com.au/membership