Man, it really depends on your substance, where I'm from i know people who easily go through $200 Aud a week on alcohol since it's so heavily taxed.
Then coke addicts who can burn 800 a week if they have the funds which is insane.
Pot heads will do 500 a month
Sometimes therapy is cheaper.
Not that i can talk i burn my money on alcohol at the pub because it gives me a place to socialise. I wish I didn't though since my local pub is 31 dollars for 4 beers and I can easily drink 8 on a Tuesday night.
Maybe I should go to therapy