Just got an email from Spintel, get $25 credit towards your first bill which will offset the normal signup fee and SIM delivery cost.
Feel free to use a referral link on
https://www.ozbargain.com.au/wiki/spintel_referral_links
and get an additional $10 or more credit
More info on referral here
https://www.spintel.net.au/referafriend
FYI, this is for new services. Existing customers can receive the credit too if they start a new service on their current account.