Just to reiterate my last post, having just read other comments. Please do not spend money on going to other consulates, other than what’s local to you. I’ve done non o visas in Penang, Singapore and HK, and I’m from the UK. Due to work circumstances I’ve never converted them to extension of stay until now- took me 2 visits to Pattaya immigration to ensure my documents for the extension were right! So if you need any pointers just shout.

The 400k doesn’t apply for the single entry 90 day non o. You will need it only when you apply for the extension when in Thailand.