You can now enter with 60 day visa exempt. Makes the old 60 day tourist visa extinct. When you have 30 days left you can extend for another 30 days for 90 days total for ฿1900.
Agents prefer that you come in visa exempt or other short term tourist visa. They know how difficult it will then be to open a bank account for the required 800k BEFORE you can apply in-country for a non-o. Applying via evisa before you arrive will provide you a Visa that makes it much easier to open an account on your own and will give you a month in country to find a place to live and open the account. It takes the agents out of the equation. You can still use one of you don't have the 800k but they become unnecessary.