I hear you sir, I personally had a very bad experience with immigration which was no fault of my own several years back and have used an agent ever since. The money really doesn't mean anything to me due to the convenience and lack of any stress. But to each their own. 😀
Its the equivalent of 20,000 baht in any currency. But, immigration almost always only ask to see money for those who are abusing the system. (e.g. too many visa exemptions in a year, countless back to back covid extensions, etc.)
I could be wrong, but when I applied for an e-visa I remember having to send in my flight itinerary as well (at least for the Los Angeles consulate office). I believe the flights should match whichever country's consulate you're applying from.
You should be able to get a tourist visa if you supply the necessary information. I'm not sure what the procedure is like in India but it's fairly easy to do on your own. My friend in Bangkok actually takes online classes for his ED visa through a school but it still requires a time commitment of several hours on Monday through Friday.