4 visa options for parents migration. Costs and waiting periods vary in inverse ratio.
Parent (Migrant) Visa (Subclass 103)
http://www.immi.gov.au/migrants/family/103/
Cost: $3,245/parent
Aged Parent (Residence) Visa (Subclass 804)
http://www.immi.gov.au/migrants/family/aged/804/
Cost: $4,085/parent
Based on current planning levels, parent category visa applicants can expect an approximate 20 year wait before visa grant consideration after being allocated a queue date.
Check waiting period - Queue Date Calculator: https://www.ecom.immi.gov.au/qcalc/QDateAnswer.do
Contributory Parent (Migrant) Visa (Subclass 143)
http://www.immi.gov.au/migrants/family/parent/143/
Cost: $39,700/parent
Contributory Aged Parent Visas (subclass 884 or subclass 864)
http://www.immi.gov.au/migrants/family/parent/864/
Cost: $40,540/parent
Based on current planning levels new contributory parent category visa applicants can expect to wait up to 2 years before visa grant consideration.