We are 9 paxs arriving midnight 12.30 am morning just wonder taxi or bus still available or taxi cost in guangzhou

Don't worry! Buses and taxis are still available at that time.
Shuttle bus line 1 to the local Railway Station and line 6 to East Train Station will not stop service until the arrival of the last flight, so you may catch that.

As for taxi, what is your destination? Anyway, I heard the taxi fare from the airport to the city center at midnight is around CNY100.