Google suggests you can buy it as a research chemical (here have this random white power...).
That said, I did find ketamine to be an extremely effective anti depressant with the primary effects being immediately noticeable and positive. I currently re-dose on ketamine every couple months and take bupropion daily--between all of these I've been able to greatly reduce fairly severe depression that went untreated and worsened over a 10+ yr period.