Mine is less than $500, but I actually spend way more than that. I live with a girl inherited her grandmother's condo (mortgage free), so no rent. I don't eat much, so food costs are low. I have British citizenship so I don't need health insurance. I live in one of the most car unfriendly cities in the world (San Francisco) so I don't own one. I could probably get by on $200 a month.

I spend close to 10x that however. Having zero expenses is murder on your spending.