Having a family and 4 kids, the best business project you could have with this amount of money is no project at all.
There are a lot of bets you can place and silly decisions you can make being on your own (especially abroad, lol), that you can't being the bread winner of a whole family.
I can understand you thought about using an agent applying for the first time (even if the process is not that complicated, having the 800k), but in your situation (very easy one for them) agents should never ask you for more than between 8.000 Thb and 15.000 Thb, period.
So 30.000 Thb is just a monumental rip off.
If you do use an agent this time, do it on your own next year for your 1 year extension, as you"ll be on easy street being familiar with the whole process then (just pay attention to everything your agent will ask you and do for ya the first time) .
You can only apply for a Non OA visa outside of Thailand.
Coming to Thailand on a 30 days visa exemption that you can extend easily at the immigration for 30 more days (1900 Thb), you've got plenty of time to then apply for a Non O visa.
You might wanna use an agent for your first time though, to make it all smoother for you (cause not that evident of a procedure the first time).
What's the point of asking why things have to be done a certain way instead of another, when you KNOW the answer (if any) will not change the way they asked you to do it in the first place ?
Why spending so much energy in vain (or did you really expect a different outtake after stating their rules and regulation were stupid) ?
Why a different country would have a different culture, mindset, logic, approach to things, different procedures for these cause their own take on them, that we couldn't all come to challenge and try to put a new spin on ?
Why don't we ever hear any complaint from people when all those same differences listed above benefit or please them ?
I find great the fact that you shared your experience here, as it will certainly be helpful to some people, so big kudos to ya for that.
However, I founded really weird to try to show them how non sense they were, by being illogical yourself.
Yeah, questioning the rules and regulation was illogical, complaining onsite about them was illogical, expecting a different treatment after that was illogical and not peeping that your whole take on it was wrong and inaccurate is illogical too.