I'm not real platinum user,but what about u create title for plat user,just like gold title..here my suggestion :

1) 1.000 plat
- get title "Platinum"
- 0 aps
- get banner

2) 5.000 plat
- get title "Purchaser"
- 0 aps
- get banner

3) 10.000 plat
- get title "Money waster"
- 0 aps
- get banner

Thx