To answer your question you need the equivalent of 800k BHT in your own bank account in which ever country and currency you reside. Just one bank statement dated the same date as your application. Once in Thailand open the Thailand bank account and move the funds across. Job done
A dbs will do it - just go online you can use an agency or do it yourself which can also be expedited. You don’t need ACRO which takes forever, unless they have changed the rules again.