I didn’t apply for it myself, buuut if it helps, I was given a 60-day stay when I entered Thailand, and before it expired, I extended it at immigration for another 30 days for around $30 USD. For about $30 more, you can also do a quick trip to Malaysia and re-enter Thailand, which gives you another 60 days. But of course, that involves a bit of moving around and time (muuuch time)
Oh! And I heard about a guy who applied for the DTV straight at the Thai consulate, and he got it in just 3 weeks. No agency, no crazy fees. He said it was super straightforward as long as you have your docs in order, it’s all pretty smooth.