Ketamine should be a fairly cheap treatment, but there are lots of ways that many involved will try to extract money out of 'doing good'. Check out this take [1] by Slate star codex.
Scott Alexander (the SSC guy) has recently said some cautiously positive things about Zembrin for depression and social anxiety. It is OTC, and apparently quite safe.
Note that he's switched to a different URL for his blog; that may be why you couldn't find it -- although I'm pretty sure he mentioned it on the old site several times as well.