You don't need $30,000.00 US you only need about $23,000.00 US (800,000 baht) in the Bank for the retirement visa. The US Embassy won't certificate your income so you can't use combination.
After you get you retirement visa you can transfer the equivalent of 65,000 baht into your bank account every month then when you renew your visa you can show the monthly income.
The 800K will be in the account 4 months before I return to Thailand. The question is will I still be required to apply for the 90 day O visa first or can I apply directly for the retirement visa??