Experience building a detached ADU in Los Angeles?

[Jackie Tayra]

Hi everyone, I would love to hear from anyone who has experience/knowledge on building a detached junior ADU (about 300 sq feet) in Los Angeles. I would like to keep it at maximum $30k but cost estimates online are saying $100k+...is it possible to do it within this budget if I do a lot of it myself? Also wondering if anyone has an estimate for how much city permit/other fees would cost for an ADU of this size?

Any help would be greatly appreciated!! Thank you in advance.