I hadn't heard of these ADU's here in Florida, very interesting to hear about. I personally wouldnt want one until my kids have gone off to college as well. $150,000 is prohibitive i would think. I paid a little more than that for my house .
Your lot appears to be a corner lot, which does give some advantages, but I think you’d want at least 1/3rd to 1/2 acre to have an ADU. You can do a pier foundation, which would solve some problems, but that estimate does seem quite high to me. Your property tax is going to go up quite a bit as well. The loss of privacy would be a big deal for many people as well.
Great video as always, Parris! If you ever build this, I could make your life a lot easier by moving in and becoming your tenant! LOL! BTW, you look fantastic!!!